When comparing Validator pro vs JSLint, the Slant community recommends Validator pro for most people. In the question“What are the best JavaScript linting tools?” Validator pro is ranked 4th while JSLint is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Validates files connected to website
Pro Enforces a very high standard
Since it's relatively old (it was made in 2002) and made by Douglas Crockford, considered a JavaScript God by many JavaScript programmers. It was created to enforce what in Crockford's experience are the good parts of JavaScript. This means that it's considered by many the best way to enforce the highest standards in JavaScript.
Pro No setup required
JSLint comes preconfigured and ready to be used.
Cons
Con Highly opinionated
JSLint has a very strict, dogmatic ruleset that cannot be changed or warnings turned off. So much so that rarely any code will pass JSLint tests. It's reasonable to evaluate if all warning are worth changing.
Con Difficult to know which rule is causing which error
Since you can't edit the rules and it's not programmed in a way to display the rule that's being broken, it's difficult to understand which rule has been broken.