本地对象Array的原型扩展

Array.prototype.del=function(){
    var b={},c,i=0,l=this.length,j;
    for(;i<l;i++){
        c=this.shift();
        c in b ? b[c]++ : b[c]=0;
    }
    for(j in b){
        if(b[j]>0)this.push(+j||j);
    }
    return this;
}
var a=[1,2,2,3,3,3,'a','b','b'];
alert(a.del());

Array.prototype.del=function(){
    return (function (i, n, j, u, o){
        for (; i < j; i++) {
            o = this[i];
            o in u ? 0 : (u[this[n++] = o] = 1)
        }
        this.length = n;
        return this        
    }).call(this, 0, 0, this.length, {})
}
var a=[1,2,2,3,3,3,'a','b','b'];
alert(a.del())