Here you can find the source of first(f)
Array.prototype.first = function(f){ var i = 0;//from ww w . j av a 2s . c o m while(i < this.length){ if(f == undefined){ return this[i]; } if(f(this[i])){ return this[i]; } i++; } return null; };
Array.prototype.first = function(fn) { if (Object.prototype.toString.call(this) !== '[object Array]') { throw new TypeError("`this` must be Array, not " + typeof this); if (typeof fn === 'undefined') { return this[0]; if (typeof fn !== 'function') { throw new TypeError("Optional `argument[0]` must be predicate function if defined"); ...
Array.prototype.first = function(func) { return this.where(func)[0]; };
Array.prototype.first = function(func) { var result = []; for(var i=0;i<this.length;i++) if (func(this[i])) return this[i]; return null;
Array.prototype.first = function (func) { var length = this.length, item = null; for (var i = 0; i < length; i++) { if (func(this[i])) { return this[i]; return item; ...