megesort.js

Array.prototype.mergeSort=function(){
    var merge=function(left,right){
        var final=[];
        while (left.length  && right.length) {
            final.push(left[0] <= right[0] ? left.shift() : right.shift() );
        }
        return final.concat(left.concat(right));
    }
    // 递归结束
    if (this.length < 2) {
        return this;
    }
    var leftArray=this.slice(0,parseInt(this.length/2));
    var rightArray=this.slice(parseInt(this.length/2));
    return merge(leftArray.mergeSort(),rightArray.mergeSort());
}

a=[234,55,667,778,234,664,2245,10239, 4321] ;
console.log(a.mergeSort())