Question

…or what’s the proper name for some() and every(). Basically, I’m looking for a function or a plugin that would allow me to write something like:

okay = $("#myForm input").every(function() { 
     return $(this).val().length > 0
})

or

hasErrors = $(listOfUsers).some(function() {
   return this.errorCount > 0;
})

You got the idea.

(Before the what-have-you-tried squad arrives, I googled and found jquery.arrayUtils, but that code doesn’t look convincing to me).

Answer 1

A simple, straightforward implementation:

$.fn.some = function(callback) {
    var result = false;
    this.each(function(index, element) {
        // if the callback returns `true` for one element
        // the result is true and we can stop
        if(callback.call(this, index, element)) {
            result = true;
            return false;
        }
    });
    return result;
};

$.fn.every = function(callback) {
    var result = true;
    this.each(function(index, element) {
        // if the callback returns `false` for one element
        // the result is false and we can stop
        if(!callback.call(this, index, element)) {
            result = false;
            return false;
        }
    });
    return result;
};

---

With ES5, arrays already provide the methods every and some, so you could achieve the same with built in methods:

okay = $("#myForm input").get().every(function(element) { 
     return $(element).val().length > 0
});

but it won’t work in older IE version without HTML5 shim.