JS使用合并数组

var arr= [4,5,6];
var arr1 = [7,8,9];
var arr2=[1,2,3];
arr.concat(arr1,arr2);

//或者使用Arry.prototype.push.aplly(mergeTo,mergeFrom);

arr; [4,5,6,7,8,9,1,2,3];