javascript扩张Array类

Array.prototype.clear = function() {
    this.length = 0;
}

varoldArrayIndexOf = Array.indexOf;//判断是否原始浏览器是否存在indexOf方法
Array.prototype.indexOf = function(obj) {
    if(!oldArrayIndexOf) {
        for(vari = 0, imax = this.length; i < imax; i++) {
            if(this[i] === obj) {
                returni;
            }
        }
        return-1;
    } else{
        returnoldArrayIndexOf(obj);
    }
}

Array.prototype.contain = function(obj) {
    returnthis.indexOf(obj) !== -1;
}

Array.prototype.insertAt = function(index, obj) {
    if(index < 0) index = 0;     if(index > this.length) index = this.length;
    this.length++;
    for(vari = this.length - 1; i > index; i--) {
        this[i] = this[i - 1];
    }
    this[index] = obj;
}

Array.prototype.last = function() {
    returnthis[this.length - 1];
}

Array.prototype.removeAt = function(index) {
    if(index < 0 || index >= this.length) return;
    varitem = this[index];
    for(vari = index, imax = this.length - 2; i < imax; i++) {         this[i] = this[i + 1];     }     this.length--;     returnitem; }

Array.prototype.removeAt = function(obj) {     varindex = this.indexOf(obj);     if(index >= 0)
        this.removeAt(index);
}

Array.prototype.select = function(args) {
    varnewItems = [];
    if(typeof(args) === "object"&& arguments.length === 1) {//传入查询的参数为对象时的处理方式
        for(vari = 0, imax = this.length; i < imax; i++) {
            varitem = {};
            for(varkey inargs) {
                if(args[key] !== undefined) {
                    item[key] = this[i][key] === undefined ? "undefined": this[i][key];
                }
            }
            newItems.push(item);
        }
    } elseif(typeof(args) === "string"&& arguments.length === 1) {//传入参数为字符串，且只有一个参数的处理方式
        for(vari = 0, imax = this.length; i < imax; i++) {
            varitem = {};
            varkeys = args.split(',');
            for(vark = 0, kmax = keys.length; k < kmax; k++) {
                variKey = keys[k].split("as");
                if(iKey.length === 1) {
                    item[iKey[0].trim()] = this[i][iKey[0].trim()] === undefined ? "undefined": this[i][iKey[0].trim()];
                } else{
                    item[iKey[1].trim()] = this[i][iKey[0].trim()] === undefined ? "undefined": this[i][iKey[0].trim()];
                }
            }
            newItems.push(item);
        }
    } else{//传入的参数是多个字符串的处理方式
        for(vari = 0, imax = this.length; i < imax; i++) {
            varitem = {};
            for(varj = 0, jmax = arguments.length; j < jmax; j++) {
                if(arguments[j] !== undefined) {
                    variKey = arguments[j].split("as");
                    if(iKey.length === 1) {
                        item[iKey[0].trim()] = this[i][iKey[0].trim()] === undefined ? "undefined": this[i][iKey[0].trim()];
                    } else{
                        item[iKey[1].trim()] = this[i][iKey[0].trim()] === undefined ? "undefined": this[i][iKey[0].trim()];
                    }
                }
            }
            newItems.push(item);
        }
    }
    returnnewItems;
}