js笔记
1.克隆对象
克隆数组：
var country=['中国','美国'];
var copyCountry=country.slice(0);克隆对象:
var people={sex:'man',age:4};
var me=JSON.parse(JSON.stringify(people));2.随机数
从数组中随机取n个不重复的元素
function getRandomArrayElements(arr, count) {
var shuffled = arr.slice(0), i = arr.length, min = i - count, temp, index;
while (i-- > min) {
index = Math.floor((i + 1) * Math.random());
temp = shuffled[index];
shuffled[index] = shuffled[i];
shuffled[i] = temp;
}
return shuffled.slice(min);
}3.回车代替点击
<button id="btnStart">开始</button>
<script>
$(function () {
$("body").keypress(function (e) {
if (e.which == 13)
{
$("#btnStart").focus().click();
}
});
$("#btnStart").click(function () {
alert("我被点击了");
});
});4.数组倒序
var a, l;
a = new Array(0,1,2,3,4);
l = a.reverse();5.获取客户端时间标准格式
function CurentTime()
{
var now = new Date();
var year = now.getFullYear(); //年
var month = now.getMonth() + 1; //月
var day = now.getDate(); //日
var hh = now.getHours(); //时
var mm = now.getMinutes(); //分
var ss = now.getSeconds(); //秒
var clock = year + "-";
if(month < 10)
clock += "0";
clock += month + "-";
if(day < 10)
clock += "0";
clock += day + " ";
if(hh < 10)
clock += "0";
clock += hh + ":";
if (mm < 10) clock += '0';
clock += mm+":";
if(ss<10) clock+='0';
clock+=ss;
return(clock);
} 格式为:yyyy-MM-dd HH:mm:ss
6.获取Url参数
function tb_parseQuery(query) { var Params = {}; if (!query) { return Params; }// return empty object var Pairs = query.split(/[;&]/); for (var i = 0; i < Pairs.length; i++) { var KeyVal = Pairs[i].split('='); if (!KeyVal || KeyVal.length != 2) { continue; } var key = unescape(KeyVal[0]); var val = unescape(KeyVal[1]); val = val.replace(/\+/g, ' '); Params[key] = val; } return Params; }
var getJsonObj = tb_parseQuery(location.href);
getJsonObj.out_trade_no
7.将数字类型保留2位小数
function changeTwoDecimal_f(x) {
var f_x = parseFloat(x);
if (isNaN(f_x)) {
alert('function:changeTwoDecimal->parameter error');
return false;
}
f_x = Math.round(f_x * 100) / 100;
var s_x = f_x.toString();
var pos_decimal = s_x.indexOf('.');
if (pos_decimal < 0) {
pos_decimal = s_x.length;
s_x += '.';
}
while (s_x.length <= pos_decimal + 2) {
s_x += '0';
}
return s_x;
} 8.数组去除重复
var unique = function(arr) {
var result = [], json = {};
for (var i = 0, len = arr.length; i < len; i++){
if (!json[arr[i]]) {
json[arr[i]] = 1;
result.push(arr[i]); //返回没被删除的元素
}
}
return result;
};9.字符串按照字符拆分放进数组
var a=Array.prototype.join.call('hello', '-');
var b=a.split("-")
10.从一个数组里面随机取N个元素
///从一个数组中随机取n个元素
function getRandomArrayElements(arr, count) {
var shuffled = arr.slice(0), i = arr.length, min = i - count, temp, index;
while (i-- > min) {
index = Math.floor((i + 1) * Math.random());
temp = shuffled[index];
shuffled[index] = shuffled[i];
shuffled[i] = temp;
}
return shuffled.slice(min);
}11.将一个数组随机排序
function arrayRandom() {
array = array.length ? array : array1;
var l = array.length;
array1 = [];
while (l) {
var rd = parseInt(Math.random() * l);
temp = array[rd];
array[rd] = array[l - 1];
array[l - 1] = temp;
array1.push(temp);
array.pop();
l -= 1;
}
array = array1;
}