Develop Reference

Detect old Internet explorer Javascript functions ( < ES6)

There is a web online, library or something to detect old IE functions that are not compatible with Chrome/Firefox or just ES6?
Like: document.all, event.returnValue, etc
JsHint/Jslint are not detecting them as deprecated or incompatibles

It's not quite fair to say JSLint won't tell you about deprecated properties. Let me explain.
Recall first that JavaScript is a dynamic language. You can assign any property to [almost] any object. You could assign all to window in a browser context if you wanted just by saying window.all = "Muahahaha!!! I'm evil!!!". You could add .all to a string with...
var spam = "a string";
spam.all = "I'm still evil!!!"
Or, worse, some piece of code could have changed the prototype for String (or any other object type) somewhere outside of your file. Try this in a browser console:
String.prototype.all = String.prototype.all || "This is beyond evil.";
// 'This is beyond evil.'
var spam = "spam"
// undefined
spam.all
// 'This is beyond evil.'
So JSLint doesn't, by default, check for properties on objects by names. Especially for objects that could live outside of your file's context (because JSLint lints file-by-file), it simply can't know what's happened to an object's properties and identify what's valid and what isn't.
(That's what TypeScript is for, btw.)
Unless you tell JSLint how!! -- the JSLint property directive ftw
Or you can use the JSLint property directive, which does exactly what you want, if you're willing to do some work.
If you put the property directive at the top of your file, JSLint will show errors for any properties that are used by objects on the page that aren't in that list.
For instance, try this on the official JSLint.com page:
/*property
log
*/
/*jslint browser, devel */
function mySpam() {
var spam = document.all;
console.log(spam);
}
See how I'm using document.all but all isn't in the property directive? It's going to error for me.
1. Unregistered property name 'all'.
var spam = document.all;
You might be saying, "But it will take me FOREVER to get all the good properties from my 3000 line file I'm linting into that directive!!"
Not so! Here's a tip: Paste your file, even unlinted, into JSLint.com. It will create a property directive for you in its report.
Here's one I made from AngularJS' [sic] route.js in just a few seconds:
/*property
$$minErr, $evalAsync, $get, angularVersion, caseInsensitiveMatch, create,
defaultPrevented, eagerInstantiationEnabled, extend, info, isArray,
isDefined, isObject, isUndefined, length, module, noop, originalPath,
otherwise, preventDefault, provider, redirectTo, reload, reloadOnSearch,
reloadOnUrl, routes, run, substr, when
*/
Alphabetical, even.
Now just remove the ones you don't want and presto! You'll catch everything you need.
Is this a little tedious, and will it take a little massaging/training on files that use document properly? Yes, but, again, in a dynamic language, this is close to the best you can hope for with file-by-file linters.
NOTE: If this doesn't solve your issue, however imperfectly, that's when we need to see more of your files and hear more precisely what problem you're trying to solve in practice.

Ace Editor - Remove error for specific syntax

I'm trying to make ace editor not count the following as "improper syntax" and be used for templating. Currently, I haven't been able to find anything similar that helps me work with ace and edit this. The closest I've found is Ace editor: customizing syntax error gutter which didn't really point me in a direction?
I want it so ace doesn't interpret:
var derp = %{ (whatever can go in here) }%;
both %{ and %{ respectively as an error.

Ace uses jshint for syntax checking which is not very extensible.
If you do not have a better syntax checker, you can try hooking into https://github.com/ajaxorg/ace/blob/v1.1.8/lib/ace/mode/javascript_worker.js#L118
and replace %{ ... }% blocks with expression/* ... */ like
value.replace(/%\{([^}]|}[^%])*}%/g, "window/*$1*/")
the expression is needed to keep js valid and comment to keep lines

Simple way to check/validate javascript syntax

I have some big set of different javascript-snippets (several thousands), and some of them have some stupid errors in syntax (like unmatching braces/quotes, HTML inside javascript, typos in variable names).
I need a simple way to check JS syntax. I've tried JSLint but it send too many warnings about style, way of variable definitions, etc. (even if i turn off all flags). I don't need to find out style problems, or improve javascript quality, i just need to find obvious syntax errors. Of course i can simply check it in browser/browser console, but i need to do it automatically as the number of that snippets is big.
Add:
JSLint/JSHint reports a lot of problems in the lines that are not 'beauty' but working (i.e. have some potential problems), and can't see the real problems, where the normal compiler will simply report syntax error and stop execution. For example, try to JSLint that code, which has syntax errors on line 4 (unmatched quotes), line 6 (comma required), and line 9 (unexpected <script>).
document.write('something');
a = 0;
if (window.location == 'http://google.com') a = 1;
document.write("aaa='andh"+a+"eded"');
a = {
something: ['a']
something2: ['a']
};
<script>
a = 1;

You could try JSHint, which is less verbose.

Just in case anyone is still looking you could try Esprima,
It only checks syntax, nothing else.

I've found that SpiderMonkey has ability to compile script without executing it, and if compilation failed - it prints error.
So i just created small wrapper for SpiderMonkey
sub checkjs {
my $js = shift;
my ( $js_fh, $js_tmpfile ) = File::Temp::tempfile( 'XXXXXXXXXXXX', EXLOCK => 0, UNLINK => 1, TMPDIR => 1 );
$| = 1;
print $js_fh $js;
close $js_fh;
return qx(js -C -f $js_tmpfile 2>&1);
}
And javascriptlint.com also deals very good in my case. (Thanks to #rajeshkakawat).

Lots of options if you have an exhaustive list of the JSLint errors you do want to capture.
JSLint's code is actually quite good and fairly easy to understand (I'm assuming you already know JavaScript fairly well from your question). You could hack it to only check what you want and to continue no matter how many errors it finds.
You could also write something quickly in Node.js to use JSLint as-is to check every file/snippet quickly and output only those errors you care about.

Just use node --check filename

Semantic Designs' (my company) JavaScript formatter read JS files and formats them. You don't want the formatting part.
To read the files it will format, it uses a full JavaScript parser, which does a complete syntax check (even inside regular expressions). If you run it and simply ignore the formatted result, you get a syntax checker.
You can give it big list of files and it will format all of them. You could use this to batch-check your large set. (If there are any syntax errors, it returns a nonzero error status to a shell).

How to suppress "{variable} is better written in dot notation."

Is there an option to and/or how do I suppress errors like the following?
175,14:['tracker'] is better written in dot notation.

If it's a feature and not a bug, place this at the top of your file.
/*jshint sub:true*/
If it's a bug, you should refactor your code
foo['tracker'] = bar // from this...
foo.tracker = bar; // to this!
Good post on the reasons here: https://stackoverflow.com/a/2001410/94668
As suggested by: #ThorSummoner you can use below in your .jshintrc file
"sub": true

In JSHint 1.0.0 and above you have the ability to ignore any warning with a special option syntax. The identifier of this warning is W069.
This means you can tell JSHint to not issue this warning with the /*jshint -W069 */ directive.
You can even wrap several lines of code and then reenable the warning as the example below (with a note to future you why it was a good idea):
/*jshint -W069 */
/*Disable Warning Justification:
Using bracket notation so Google Closure Compiler
ADVANCED_OPTIMIZATIONS will keep the original property names. */
obj['prop1'] ='foo';
obj['prop2'] ='bar';
/*jshint +W069 */

I assume you are asking about Dreamweaver or another editor.
Dreamweaver
You may go to Edit -> Preferences -> Linting
Select JS in the dropdown and hit Edit & Apply changes
Find
"sub": false,
and change that to true. Save the file and that notice will disappear.
If you have OTHER Linting things you wish to edit, you can find a helpful list of them all at https://jshint.com/docs/options/

Put semicolons in asi mode before brackets

I'm linting my JavaScript with JSHint, and have this option enabled
"asi": true,
"white": true
to avoid semicolons in my code.
But I have to begin my new line with a bracket, so I have to put a semicolon before the opening of that one
;(function () {
})
JSHint give me two errors:
Missing space after ';'
If I put a space after ';' I get: Expected '(' to have a different identation
I noticed that in this way JSHint is happy
;
(function () {
})
but I think is not a good solution.
Is there a way to solve this problem, without turning off JSHint or the white option?

The legacy white: true option in JSHint is used to enforce the coding style promoted by Douglas Crockford in his original JSLint tool. Semicolon-less JavaScript code will not fit his coding style. If you don't want to be restricted to his style guidelines then don't use white: true.
This list of JSHint options doesn't show any parameters to customize the coding style they enforce.
To prove that there isn't an answer to this, I went and found the relevant check in the JSHint source:
function nonadjacent(left, right) {
if (option.white) {
left = left || token;
right = right || nexttoken;
if (left.line === right.line && left.character === right.from) {
left.from += (left.character - left.from);
warning("Missing space after '{a}'.",
left, left.value);
}
}
}
The only configuration option checked is option.white, so unfortunately there isn't any way to achieve your desired behavior. If you really wanted a tool that would do exactly what you want, you could easily fork JSHint, add another option, and check it in the nonadjacent function.