Filtering in javascript

Anatoly Mironov

The simplest and the best way to filter an array is to extend the Array.prototype as described here:

if (!Array.prototype.filter) {
    Array.prototype.filter = function (func) {
        var len = this.length;
        if (typeof func != "function")
            throw new TypeError();

        var res = new Array();
        var thisp = arguments\[1\];
        for (var i = 0; i < len; i++) {
            if (i in this) {
                var val = this\[i\];
                if (func.call(thisp, val, i, this))
                    res.push(val);
            }
        }

        return res;
    };
}

```Then let's filter on [titles](/2011/11/21/sorting-dates-in-javascript/ "See an example for Sorting with Titles"), which [start with](http://stackoverflow.com/questions/646628/javascript-startswith "See the solution for startsWith in javascript on Stackoverflow") "N":

function startsWithN(element, index, array) { return element.toLowerCase().indexOf(“n”) == 0; }

var filtered = dates.filter(startsWithN);

$("#contactContainer").empty(); $("#contactTemplate").tmpl(filtered).appendTo("#contactContainer");