javascript - 内置对象 String/Date/Array/Math

1.构建对象的方法#

<script>
        //构建对象方法
        //第1种
        var people = new Object();
        people.name = "iwen";
        people.age = 26;
        document.write("name:" + people.name + ",age:" + people.age + "<br>");

        //第2种
        people1 = { name: "zhangsan", age: 27 };
        document.write("name:" + people1.name + ",age:" + people1.age + "<br>");

        //第3种
        function peopleConstructor(name, age) {
            this._name = name;
            this._age = age;
        }
        son = new peopleConstructor("liuz", 28);

        document.write("name:" + son._name + ",age:" + son._age + "<br>");
    </script>

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2.String字符串对象#

1.查找：indexOf()#

2.内容匹配：match()#

        var str = "Hello World";
        //匹配
        document.write(str.match("World")+"<br>");
        document.write(str.match("world"));

 

3.替换:replace()#

4.大小写转换：toUpperCase() \ toLowerCase()#

      //转换大写
        str=str.toUpperCase();
        document.write(str + "<br>");
        //转换小写
        str = str.toLowerCase();
        document.write(str + "<br>");

 

5.字符串转为数组：split()#

var str1 = "Hello Bai du";
        //document.write(str1 + "<br>");
        var s = str1.split(" ");
        for (var i = 0; i < s.length; i++) {
            document.write(s[i] + "<br>");
        }

 

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3.Date日期对象#

getFullYear()：获取年份

getTime()：获取毫秒

setFullYear()：设置具体日期

getDay()：获取星期

<div id="timetxt">
    </div>
    <script type="text/javascript">
        var date = new Date();
        document.write(date);
        document.write("<br>");
        //获取年份
        document.write(date.getFullYear());
        document.write("<br>");
        //获取毫秒
        document.write(date.getTime());


        startTime();

        function startTime() {
            var today = new Date();
            var h = today.getHours();
            var m = checkTime(today.getMinutes());
            var s = checkTime(today.getSeconds());

            document.getElementById("timetxt").innerHTML = h + ":" + m + ":" + s;
            setTimeout(function () {
                startTime();
            }, 2000);
        }

        function checkTime(i) {
            if (i < 10) {
                i = "0" + i;
            }
            return i;
        }

    </script>

 

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4.Array数组对象#

concat()：合并数组

sort()：排序

push()：末尾追加元素

reverse()：数组元素翻转

        document.write('--------------合并-------------<br>');
        var a = ["hello", "world"];
        var b = ["tang", "sansan"];
        var c = a.concat(b);
        document.write("c:" + c);

        document.write('<br>---------------排序------------<br>');
        var d = ["a", "c", "d", "t", "b", "e"];
        d.sort();
        document.write(d);

        document.write('<br>--------------末尾追加-----------<br>');
        var e = ["hello", "world"];
        e.push("tangsansan");
        document.write(e);

        document.write('<br>---------------翻转------------<br>');
        c.reverse();
        document.write(c);

 

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5.Math对象#

算数任务

round()：四舍五入#

random()：返回 0 ~ 1 之间的随机数#

max()：返回最高值#

min()：返回中的最低值#

abs()：绝对值#

        var num = 2.5;
        document.write('---------------Math.round------------<br>');
        document.write(Math.round(num));
        document.write('<br>---------------1~100的随机数------------<br>');
        document.write(parseInt(Math.random() * 100));
        document.write('<br>---------------最大值------------<br>');
        document.write(Math.max(num, 23, 52, 77, 32));
        document.write('<br>---------------最小值------------<br>');
        document.write(Math.min(num, 23, 52, 77, 32));
        document.write('<br>--------------绝对值------------<br>');
        var abs1 = 10;
        var abs2 = -10;
        document.write(Math.abs(abs1));
        document.write('<br>');
        document.write(Math.abs(abs2));