1.去掉数组中重复的值

Array.prototype.unique = function() {
	var data = this || [];
    var a = {}; //声明一个对象，javascript的对象可以当哈希表用
    for (var i = 0; i < data.length; i++) {
        a[data[i]] = true;  //设置标记，把数组的值当下标，这样就可以去掉重复的值
    }
    data.length = 0; 
    
    for (var i in a) { //遍历对象，把已标记的还原成数组
        this[data.length] = i; 
    } 
    return data;
};

var a = new Array("5","7","7");
alert(a);
alert(a.unique());

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2.删除数组中指定的值

Array.prototype.remove = function(val) { 
    for(var i = 0; i < this.length; i++) { 
        if(this[i] == val) { 
        	for(var j = i; j < this.length - 1; j++)
            	this[j] = this[j + 1]; 
            this.length -= 1;
        }
    }    
}

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3.在字符串的左边填充一些特定的字符

String.prototype.lpad = function(len, s) {
	var a = new Array(this);
	var n = (len - this.length);
	for ( var i = 0; i < n; i++) {
		a.unshift(s);
	}
	return a.join("");
}

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4.在字符串的右边填充一些特定的字符

String.prototype.rpad = function(len, s) {
	var a = new Array(this);
	var n = (len - this.length);
	for ( var i = 0; i < n; i++) {
		a.push(s);
	}
	return a.join("");
}

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5.获取星期几

function getWeek() {
	var a = new Array("周日", "周一", "周二", "周三", "周四", "周五", "周六");
	var d = new Date().getDay();
	return a[d];
}

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6.获取日期

function getDate() {
	var mydate = new Date();
	var y = mydate.getYear();
	var m = String(mydate.getMonth() + 1).lpad(2, "0");
	var d = String(mydate.getDate()).lpad(2, "0");
	var a = new Array(y, m, d);
	return a.join("-");
}

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7.把字符串的首字母转化为大写

String.prototype.initialsToUpper = function() {
	return this.substring(0,1).toUpperCase().concat(this.substring(1));
};

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8.判断一个字符串中是否包含某字符

String.prototype.contains = function(str) {
	return this.indexOf(str) > -1 ? true : false;
};

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9.去掉字符串的空格

String.prototype.trim = function() {
	return this.replace(/(^\s*)|(\s*$)/g, "");
};
   
String.prototype.lTrim = function() {
	return this.replace(/(^\s*)/g, "");
};
   
String.prototype.rTrim = function() { 
	return this.replace(/(\s*$)/g, "");
};

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10.操作表单元素的几个js方法

//删除下拉框选项
function removeAllOptions(obj) {
	for (var k = obj.length - 1; k > 0; k--) {
		obj.remove(k);
	}
}

//添加下拉框选项
//其中data是action传过来的TreeMap值
function appendAllOptions(obj, data) {
	removeAllOptions(obj);
//	data = data.substr(1, data.length - 2);
	var arg = data.split(",");
	for (var i = 0; i < arg.length; i++) {
		var val = arg[i].split("=");
		obj.add(new Option(val[1], val[0]));
	}
}

//通过已选中checkbox的id获取当前行第n列的值，并组合成字符串返回
function getTDText(chkId, n) {
	var temp = "";
	var ids = chkId.split(",");
	for (var i = 0; i < ids.length; i++) {
		var tr = $(ids[i]).parentElement.parentElement;
		if (temp == "") {
			temp = tr.cells[n].innerText.trim();
		} else {
			temp += "," + tr.cells[n].innerText.trim();
		}
	}
	return temp;
}

//获取一组radio选中项的值
function getRadioValue(name) {
    var obj = document.getElementsByName(name);
    if (obj != null) {
        for(i = 0; i < obj.length; i++) {
            if (obj[i].checked) {
                return obj[i].value;            
            }
        }
    }
    return null;
}

//全选或取消全选
function chkAll(ele) {
	var objArray = document.getElementsByName("chk");
	for (var i = 0; i < objArray.length; i++) {
		objArray[i].checked = ele.checked;
	}
}

//获取选中的ID
function getChkVal() {
	var ids = "";
	var objArray = document.getElementsByName("chk");
	for (var i = 0; i < objArray.length; i++) {
		if (objArray[i].checked) {
			if (ids == "") {
				ids = objArray[i].id;
			} else {
				ids += "," + objArray[i].id;
			}
		}
	}