排列数组的方法

//数组的组合
Array.prototype.combinate = function(iItems, aIn) {
if (!aIn) {
var aIn = new Array();
this.combinate.aResult = new Array();
}
for (var i = 0; i < this.length; i++) {
var a = aIn.concat(this[i]);
var aRest = this.concat(); // Concat with nothing to create copy
aRest.splice(0, i + 1);
if (iItems && iItems - 1 <= aRest.length) {
aRest.combinate(iItems - 1, a);
if (iItems == 1) this.combinate.aResult.push(a);
}
}
return this.combinate.aResult;
}
var arr = [1,2,3,4];
var newarr = arr.combinate(2);
console.log(JSON.stringify(newarr));//[[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]

 //多数组之间的排列组合方法

var comarray = function(arr) {
var  sarr  =   [
[]
];
for  (var  i  =  0;  i  <  arr.length;  i++)  {    
var  tarr  =   [];    
for  (var  j  =  0;  j  <  sarr.length;  j++)        
for  (var  k  =  0;  k  <  arr[i].length;  k++)  {           
tarr.push(sarr[j].concat(arr[i][k]));
}
sarr  =  tarr;
}
return sarr;
}

var newarr = comarray([["1","2"],["a","b"]]);//[["1","a"],[]"1","b"],["2","a"],["2","b"]]