javascript 數組擴充.

    //添加元素, 如果已經存在則不添加, 返回元素下標
    Array.prototype.addUnique=function(value){
        var index = this.findIndex(value);
        if(index>-1){
            return index;
        }else{
            index = this.length;
            this[index]=value;
            return index;
        }
    }
    //尋找數組元素, 返回元素下標
    Array.prototype.findIndex=function(value){
        var index=-1;
        for(var i=0;i<this.length;i++){
            if(this[i]===value) {
                index=i;
                break;
            }
        }
        return index;
    } 
    //刪除數組元素, 並返回元素下標
    Array.prototype.deleteByValue=function(value){
        var index = this.findIndex(value);
        if(index>-1){
            this.splice(index,1);
        }
        return index;
    }