When comparing JavaScript vs CoffeeScript, the Slant community recommends JavaScript for most people. In the question“What is the best programming language to learn first?” JavaScript is ranked 14th while CoffeeScript is ranked 65th. The most important reason people chose JavaScript is:
If you run a web browser you already have JavaScript installed and can get started right away. Modern browsers such as Chrome also have very powerful programming consoles built into them. Aside from the browser console, you can also use online Javascript playgrounds such as JS Bin and JS Fiddle. Even from a tablet.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro No installation required
If you run a web browser you already have JavaScript installed and can get started right away. Modern browsers such as Chrome also have very powerful programming consoles built into them.
Aside from the browser console, you can also use online Javascript playgrounds such as JS Bin and JS Fiddle. Even from a tablet.
Pro Required for web development
If you are looking to create web projects, you will have to learn Javascript in order to develop the client side code. If you learn the foundations of programming in JavaScript you can reapply that education later in building web applications.
Pro Massive ecosystem
JavaScript has one of the largest programming ecosystems, as shown by the being the most popular language for projects on GitHub. As there are so many projects written in JavaScript there are lots of libraries available to build off of and many of them are written to be easy to use and integrate into other projects.
There are also lots of resources available for learning JavaScript. Other than traditional tutorials, language learning sites such as Codecademy have JavaScript courses. The Mozilla Developer Database also serves as a great resource for learning about the standard libraries built into JavaScript.
Pro Easy to build an application
By using the UI capabilities in HTML and CSS you can develop substantial applications with graphical interfaces more quickly and with less effort than in other languages which would require you to learn a windowing library.
Building a useful application is one of the best ways to learn a new language and because of the low learning curve for creating applications you can create more substatial programs and learn more practical programming priciple faster.
Pro Runs on both the browser and the server
With Node.js, it is now possible to run JavaScript as a web server. This would allow you to be able to create server based applications sooner than would if you had to learn a separate programming language as well for server side code.
As JavaScript is the only language supported by web browsers it puts it in the unique situation of being the only programming language that's available on both the client side and server side.
Pro First-class functions with lexical closures
While certainly not the only language with these features, this pro alone is so powerful that it compensates for most of JavaScript's problems. You'll learn to use closures and higher-order functions well in JavaScript, because you have to. And then you can generalize this knowledge to any other language that has these, and the good ones do.
Pro High demand for JavaScript developers
If you're looking for a career as a developer, JavaScript is the place to focus your attention. There is a huge demand for good developers especially in frameworks such as React and Angular.
Pro Complete dev stack can be run online
With codepen.io and other prototyping tools, you can learn Javascript from a mobile device. You don't even need a computer. It can be learned from an internet cafe or public library.
Pro JSON is native to JS
JSON is arguably a "must-learn". With JS, that's one less additional syntax to learn.
Pro Very good debugger
Has a built in debugger with break points, watches that work on local values, and a console that you can use to edit anything at any time. Both in the browser (eg: Chrome), and server (eg: Nodejs).
Pro Can be very simple (teachable)
By setting a few ground-rules (effectively coding in a subset of JS), JS is one of the simplest languages to learn (requiring very few must-learn prerequisite concepts).
Pro Great tools for development
Flow, JSHint/ESLint, Babel, npm, etc.
Pro Several Platforms to use the web stack and JS to create multi-platform apps
Opens the door to native application development as well as just websites. Use with React Native, Weex or Quasar (Vue), PhoneGap or Cordova, NativeScript... (etc) to build native apps. Use mostly the same code base for multi-platform and web.
Pro Atwood's Law "Any application that can be written in JavaScript, will eventually be written in JavaScript."
May also be a con.
Pro Modern ESNext is far better than the JS of days past
Modern JS has made great strides, and can be targerted to older (or non-standard) browsers using Babel. There are new language constructs that can make programming in JS comfortable.; e.g.: async / await ( <3 ).
Pro Instant gratification
While it's easy to argue that Python will give you 'instant gratification' (while actually ruining your understanding of good programming practices), JavaScript is far better in this regard. Make a small change to a page and it's immediately visible in the browser. You can throw in a JavaScript library like jQuery with minimal fuss.
Pro Speed (most implementations)
JS/ES is in the running for the fastest interpreted language given the optimizations and JIT integration of popular implementations. On the other hand, it fails utterly when compared with compiled (to native or VM code) languages.
Pro Integrates very well with UE4
Coding an immersive 3D game can retain the attention of new programmers. ncsoft/Unreal.js.
Pro Prototype based Object Oriented System
Being object oriented, it supports the predominate and powerful programming approach. Being prototype based, it provides an intuitive approach to OOP. Whereas other popular languages use classes, which focus on thinking in the abstract, Javascript's prototypes allow you to focus on thinking in the concrete.
For example, in a prototypical language, you think of a rectangle, and define it. You now have a rectangle. Let's say you want a red rectangle, you copy the rectangle and give it the property red. Want a blue one? Copy rectangle again give it a blue. Big blue rectangle? Copy blue rectangle and make it big. In a class-based language, first you describe a rectangle, describe a red rectangle as a type of rectangle, describe blue and big blue rectangles, and now that you have described them, you must create instances of them, and only then do you have the rectangles. Essentially: Classes are factories for objects, prototypes are objects themselves, and the latter method was created to be more intuitive, which is particularly advantageous to beginners.
Pro C-like syntax
After learning Javascript, you will feel at home in other languages as C-like syntax is very common.
Pro One of the most underestimated languages
deviously simple in syntax, yet highly powerful in paradigms, this language does not force you to the (actually intrinsically broken) object oriented paradigm, has a healthy dose of functional programming inside, and does not bloat the keyword space. Good javascript is all about structure. Bad javascript is all about lazy hipsters not taking the time to learn 'javascript, the good parts', a must read.
Pro Extremely popular
JavaScript usually tops the lists for most popular languages in use today and rightly so. It's used almost everywhere and it's in high demand, making it very easy to find a job for anyone who knows JavaScript. This helps make it desirable for a first language, as it will often be used in the future.
Pro The most used language in the whole Solar System in amount of scripts/applications
Because it runs in many different environments, it is the most used language in the world.
Pro Compiles to readable Javascript
With CoffeeScript, there's never really a question of what is going on. If you're worried that something went wrong in the compilation process, the output is very human readable and mostly 1 to 1 with the CoffeeScript code, making debugging easier as the code that is being executed by the interpreter can be double checked.
Pro Widely used
CoffeeScript is the most popular of the compile to Javascript languages, so long term support is much less of a worry than with others.
It also means there are many plugins and tools for integrating it into many different build systems, giving it it nearly universal support.
Pro Lightweight syntax
Javascript is a very verbose language so CoffeeScript's goal is to lighten it to make it less tedious.
Various design choices are built around making CoffeeScript more terse with things like optional parenthesis in function calls, cleaner function declarations, no curly braces, and significant white space. Because Javascript can get pretty deeply nested at times, having a lightweight syntax helps with readability.
The result is a language with a minimalistic syntax with lots of syntax sugar.
Pro It's just JavaScript
The golden rule of CoffeeScript is: "It's just JavaScript". The code compiles one-to-one into the equivalent JS, and there is no interpretation at runtime. You can use any existing JavaScript library seamlessly from CoffeeScript (and vice-versa). The compiled output is readable and pretty-printed, passes through JavaScript Lint without warnings, will work in every JavaScript runtime, and tends to run as fast or faster than the equivalent handwritten JavaScript.
Pro Syntax for humans, not compilers.
CoffeeScript adds syntax that is not only more terse than javascript, smoothing over the rough edges, but also enforces a more human readable syntax to the point where a non-programmer can understand some logic.
Many programmers that are not use to coffeescripts syntax will find it foreign if they don't read the single page API, but generally it is quick to understand and although self documenting code is a myth coffeescript is definitely very close.
if hungry then eat food for food in fridge when food isnt poison and it isnt bedtime
Seems a lot more concise and comprehensible to many programmers and most others than the alternative syntax:
var food, i, len;
if (hungry) {
for (i = 0, len = fridge.length; i < len; i++) {
food = fridge[i];
if (food !== poison && it !== bedtime) {
eat(food);
}
}
}
Pro Function syntax is great for callbacks
Passing functions as callbacks is central to how Javascript is written, but the default syntax for functions is very verbose and hard to read. Various CoffeeScript syntax decisions help with ease of writing and reading functions.
The most obvious change is that the function keyword is changed from function
to ->
. Writing out the word function
is very clunky especially when you need to use multiple nested functions.
One of the more opinionated choices of CoffeeScript is the use of significant whitespace, and optional parens around function arguments. While this can be used poorly, it can also be used to great effect with nested functions. For example, a function that takes an object that defines anonymous functions will end in a mess of parens and curly braces:
asyncAction({
success: function(data){ /* handle data */ },
error: function(error){ /* handle errors */ }
});
In CoffeeScript you could rewrite this as:
asyncAction
success: (data) -> /* handle data */
fail: (error) -> /* handle errors */
Other helpful features are automatic returning of the last statement to make short anonymous functions easier so (a, b) -> a+b
would replace function (a, b) { return a+b; }
, as well as binding functions to the current context object with =>
.
Pro Splats
Because Javascript functions can take variable amounts of parameters, it is helpful to be able to use splats to extract an array of arguments in a function.
For example, if you have a function like: (a, b, rest...) ->
any amount of parameters sent to the function after a
, b
will be stored in an array in the variable rest
. You can also put splats at the start or middle of the arguments list, such as (a, middle..., b) ->
.
When calling a function you can use a splat to apply an array as arguments as well.
Pro Everything is an expression
Even for
loops and if
statements. For example, to get mapped array, you don't have to use any Array methods, just the language features:food = ( stuff for stuff in fridge when stuff.isEatable() )
Pro Familiar to Ruby programmers
CoffeeScript was created by a Ruby programmer and a number of syntax features are modelled on Ruby equivalents, so will be familiar to Ruby programmers. For example, implicit returns, i.e. the last variable of each function is implicitly returned, so "return" keyword need not be present.
Pro Extremely easy to document with literate coffeescript
Skip the documentation build, just write documentation with literate CoffeeScript.
CoffeeScript has a literate mode which let's you use markdown (used by almost everything, such as reddit, github, stack exchange, etc) with code indented how you would normally in markdown and simply enables you to run the code.
This enables you to quickly write FORMATTED, custom documentation that's easily displayed with no build step for the documentation.
Pro Source maps allow you to debug code in CoffeeScript
With source maps, you can get the proper location of where an error occurred directly in precompiled code, making it easier to debug without the tedious step of translating the compiled code back to the original code in your head.
Pro Significant whitespace
Having indention-based code blocks is particularly helpful in JavaScript because of its functional callback based nature. In JavaScript you find yourself writing functions within object and passing functions to functions. You can find statements ending with a confusing melange of braces like )}})})
. With significant whitespace, most of the needs for braces go away.
Pro Default choice for Ruby on Rails
Pro Maintainable code
Easy to read and easy to work with structures like list.
Cons
Con Many errors pass silently
JavaScript looks for every possible way to treat the code you write as runnable and is very reluctant to point out likely errors. For example, you have call a function with too many arguments, the extra arguments are simply discarded.
Con Easy to accidentally use globals
If you forget a var
or new
, you can clobber the global scope. For tiny scripts (JavaScript's original use case) globals are great, but for larger applications globals are generally regarded as a Bad Thing. This is because changes to one small part of a program can randomly break things anywhere else. These kinds of bugs are notoriously hard to find.
Con Does not teach you about data types
Since JavaScript is a weakly typed language, you don't have to learn about data types if you start using JavaScript as your first language. Data types being one of the most important concepts in programming. This will also cause trouble in the long run when you will have to (inevitably) learn and work with a strongly or statically typed language because you will be forced to learn the type system from scratch.
Con Weird type coercions
'5' - 1 == 4
, but '5' + 1 == 51
. There are other examples that make even less sense.
Con Complex
JavaScript has a long litany of warts and gotchas. JavaScript will bite you if you're just a wee bit careless. You have to exercise a great deal of caution and awareness. You either have to know the entire 545-page ES6 spec to avoid them all, or use a linter to help restrict you from using the bad parts (and you still have to be familiar with the language), but beginners don't know these things. (Linters are also prone to time-wasting false positives.) This is a significant cognitive burden on even the experienced programmer (as if coding wasn’t hard enough already), but try learning to program in the first place on top of all of this and you'll understand that JavaScript is a terrible choice for the beginner.
Con Easy to fall into bad manners and bad mind structure
It wouldn't consolidate a good mind structure for moving to other languages. Too open.
Con Each browser has its own quirks when executing the same code in some cases
Beginner programmers often make the mistake of coding something, seeing it works in the browser they tested it in, and then scratching their heads when it doesn't work in another browser. Ideally you'd want a language that works consistently across all platforms in order to be able to focus more on the programming and less on the underlying environment. It just takes time away from learning and forces you to spend time figuring out why this worked in browser X but not browser Y.
Con The constant churn of tooling and language
Trying to keep up=javascript fatigue. You won't have time to learn anything else if this is your first language, and you will probably think all programmers are crazy. Plus web assembly may open the door for better alternatives.
Con Very confusing to read
Con The "this" keyword doesn't mean what you think it means
this
is bound to whatever object called the function. Unless you invoke it as a method. Unless you invoke it as a constructor. Unless it's an arrow function.
Con Limited standard library
Much often needed functionality is not in the standard library. (Contrast with Python.) However, there are well established libraries such as Lodash, to fill the gap (however, due to the diverse/fractured ecosystem it may not be clear what library to use).
Con Many tutorials, code, and resources, are structured for older ES5 code
Con Asynchronous coding is not easy for beginners
JavaScript can work synchronously but its current use is mainly around asynchronous instructions, and it's surely not a good way to start learning programming.
Con The `null` and `undefined` objects aren't really objects
Therefore, attempts to call methods on them will fail. This is especially frustrating since these are often returned instead of throwing exceptions. So a failure may appear far away from the actual cause, which makes bugs very hard to find.
Con Array-like objects
Many cases when you should get an Array, you just get an Array-like object instead and none of the Array methods work on it.
Con Fast moving
The language and the web platform move fast these days. this makes it difficult for students as there is a lot of fragmentation and outdated information.
Con Numbers that begin with 0 are assumed octal
This is very surprising for beginners. Especially since 00
through 07
seem to work just fine. And this isn't just for hardcoded numbers. The parseInt()
function has the same problem, but only on some systems.
Con Good tools are pretty much a MUST for new programmers
You really want to be using a good editor (light IDE) and a linter, type checker (e.g.:Flow), etc. until you grok the language. And choosing / setting-up that development environment is it's own learning curve. If taught in a classroom, using a subset of JS with solid tools, there is an argument that JS could be an ideal first language... however, that is a lot of ceremony to protect the new programmer from JS gotchas. But without the tools, JS can be a very painful painful first language (trying to figure out why your code isn't doing what you intended).
Con The language itself is not very appealing to developers.
JS is one of the most dreaded languages as it was designed for the purpose of becoming just an scripting language for a browser. It was never intended to take over as the leading technology in web development, thus the language has been streched past its own capabilities. A beginer should learn something else first, something that is better conceived and refined.
Con Counter-intuitive type conversion
JavaScript is rather inconsistent when dealing with different types. For example, when working with the + operator and two numbers, they will be added, two strings will be concatenated:
3+5; // 8;
"Hello "+"world"; // "Hello world"
When using +
with a string and a non-string operand, the non-string operand is converted to a string and the result is concatenated:
"the answer is "+42; // "the answer is 42"
"this is "+true; // "this is true"
In any other case (except for Date) the operands are converted to numbers and the results are added:
1+true; // = 1+1 = 2;
null+false; // = 0+0 = 0;
Con Fractured ecosystem
Angular, React, Ember, Meteor, Backbone, Knockout, Express, Mithril, Aurelia. The web frameworks pass in and out of fashion too quickly to keep up with. The endless civil wars are becoming tiresome.
Con Has really bad parts you're better off avoiding altogether
But beginners won't know better. And even after you learn, you might have to deal with others' code that uses the bad stuff. JavaScript was originally developed in 10 days. It just wasn't designed that carefully.
Con Terse syntax can lead to ambiguity
It can sometimes be hard to be sure of what CoffeeScript will compile down to because of the optional parentheses and significant white spacing. Over multiple lines the same statement can be written in many different ways, and it's not always clear what the intended interpretation is.
For example:foo bar and hello world
can compile to either:
foo(bar) && hello(world)
foo(bar && hello(world))
Con Initializing a variable and assigning it are essentially the same thing
Because of how variables are initialized and reassigned in CoffeeScript, it becomes very easy to accidentally overwrite a variable as the codebase increases. As complexity increases, the only way to safely create a variable is by pressing Ctrl + F and by examining the current file to ensure that there's no conflict.
Con Last expression is returned by default
While this is a pro for small functions, it requires self-discipline to check if unnecessary overheads are introduced:
eat_full = ->
for food in fridge
break if full
cook food if food.requires_cooking()
eat food
This will return array of eat
function results. Can be fixed by adding empty return
at the end.