prototype.js分析 Enumerable

JavaScript

invoke() 各要素にメソッドを適用する

<script>
Array.prototype._each = function(iterator){
	for(var i=0, l=this.length; i<l; i++){
		iterator(this[i]);
	}
};

Array.prototype.each = function(iterator){
	var index = 0;
	try{
		this._each(function(v){
			iterator(v, index++);
		});
	} catch(e){
		if(e != $break) throw e;
	}
};

Array.prototype.collect = function(iterator){
	var iterator = iterator || function(x){return x};
	var rs = [];
	this.each(function(v, k){
		rs.push(iterator(v, k));
	});
	return rs;
};

Array.prototype.invoke = function(method){
	var args = $A(arguments).slice(1);
	return this.collect(function(v, k){
		return v[method].apply(v, args);
	});
}

function $A(iterable){
	if(!iterable) return [];
	if(iterable.collect) return iterable.collect();
	var length = iterable.length, rs = new Array(length);
	while(length--) rs[length] = iterable[length];
	return rs;
}

var $break = {};

var kekka = "hoge,moge,dada,yonsama".split(',').invoke('toUpperCase');
console.log(kekka);

var kekka = "hoge,moge,dada,yonsama".split(',').invoke('substring', 0, 2);
console.log(kekka);

//applyの例
var test = 'hoge';
console.log(test.toUpperCase.apply(test));
console.log(test.substring.apply(test, [0,2]));
</script>