js 获取10个不重复随机数

	var arr1 = new Array();
			var arr2 = new Array();
			for(var i = 0; i<20; i++){

				arr1.push(i);

			}

			for(var k = 0; k<10;k++){

				var id = Math.ceil(Math.random()*19);
				if(arr2.indexOf(arr1[id]) === -1){
					arr2.push(arr1[id]);
				}else{
					k= k - 1;
					continue;
				}
			}

			console.log(arr2);