Clean way to remove element from javascript array (with jQuery, coffeescript)

Peter picture Peter · Jan 28, 2011 · Viewed 62.6k times · Source

There are many questions about this, not least: jQuery version of array contains, a solution with the splice method and many more. However, they all seem complicated and annoying.

With the combined powers of javascript, jQuery and coffeescript, what is the very cleanest way to remove an element from a javascript array? We don't know the index in advance. In code:

a = [4,8,2,3]
a.remove(8)     # a is now [4,2,3]

Failing a good built-in method, what is a clean way of extending javascript arrays to support such a method? If it helps, I'm really using arrays as sets. Solutions will ideally work nicely in coffeescript with jQuery support. Also, I couldn't care less about speed, but instead prioritize clear, simple code.

Answer

Amir picture Amir · Jan 28, 2011

CoffeeScript:

Array::remove = (e) -> @[t..t] = [] if (t = @indexOf(e)) > -1

Which simply splices out the element at position t, the index where e was found (if it was actually found t > -1). Coffeescript translates this to:

Array.prototype.remove = function(e) {
    var t, _ref;
    if ((t = this.indexOf(e)) > -1) {
        return ([].splice.apply(this, [t, t - t + 1].concat(_ref = [])), _ref);
    }
};

And if you want to remove all matching elements, and return a new array, using CoffeeScript and jQuery:

Array::remove = (v) -> $.grep @,(e)->e!=v

which translates into:

Array.prototype.remove = function(v) {
    return $.grep(this, function(e) {
        return e !== v;
    });
};

Or doing the same without jQuery's grep:

Array::filterOutValue = (v) -> x for x in @ when x!=v

which translates to:

Array.prototype.filterOutValue = function(v) {
    var x, _i, _len, _results;
    _results = [];
    for (_i = 0, _len = this.length; _i < _len; _i++) {
        x = this[_i];
        if (x !== v) {
            _results.push(x);
        }
    }
    return _results;
};