Promise.all()方法的实现

function promiseAll(promises){
	return new Promise(function(resolve,reject){
		if(!Array.isArray(promises)){
			return reject(new TypeError("argument must be anarray"))
		}
		var countNum=0;
		var promiseNum=promises.length;
		var resolvedvalue=new Array(promiseNum);
		for(var i=0;i