Question

I am currently running JSLint against the javascript in my web application and getting some errors that I require assistance with resolving.

a. First error I am getting is: JS Lint: Unused Variable ‘n’.

 $.each(collection, function (n, item) {
                var temp = item.Id;
        // do further processing
    });

b. I have all my javascript declared in a self executing function like such:

(function ($, undefined) {
// further javascript code
}
(jQuery));

The above pattern can protect the $ from conflicting with other JavaScript libraries and also protect undefined from being redefined. However I get these errors from it:

JS Lint: Expected an identifier and instead saw ‘undefined’ (a reserved word).
JS Lint: Unused Variable ‘undefined’.

c. JS Lint: Unescaped ‘-‘.

 if (value.match(/^[A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4}$/i)) {
    return true;
 }

d. JS Lint: Type confusion: ‘printer-‘: string and ‘(‘: number.

  var frameName = "printer-" + new Date().getTime();

I get numerous errors of Type confusion, sometimes with numbers, integers and other data types. Any idea as to how I can prevent getting these?

e. JS Lint: Insecure ‘^’.

var value = value.replace(/[^\d\.,\-]/gi, '');

f. JS Lint: Don’t make functions within a loop.

for (i = 0, l = txts.length; i < l; i += 1) {
        if (/^[0-9]+$/.test(txts[i].getAttribute("maxlength"))) {
            var func = function () {
                //do some processing
            };
        }
    }

Answer 1

A.) See: http://api.jquery.com/jQuery.each/

you can use:

$.each(collection, function() {
    doSomething(this); // this refers to the current iteration
});

B.) If you aren’t actually using “undefined” you aren’t protecting it from anything

C.) I’m not going to bother with regex lol EDIT: Perhaps it wants [A-Z0-9\-]

D.) You are concatenating string with number. Try 'string' + Date.getTime().toString() instead

See also JSLint Type Confusion: function and object with jQuery .css() for type confusion stuff, there are some oddities that I don’t agree with

E.) Again I’m not going to try for the regex EDIT: Here’s an identical question though: JSLint "insecure ^" in regular expression

F.) If you can create your function once outside of the loop and then use it inside the loop (as long as you do it well) it is a significant performance increase.