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Detailed explanation of JS native objects and regular expressions

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Release: 2018-03-17 16:13:16
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This article mainly shares with you the detailed explanation of JS native objects and regular expressions. There are string objects, array objects, date objects, mathematical objects and regular expressions respectively. I hope it can help everyone.

Hope it helps everyone.

1. String object

<script type="text/javascript">
    // charAt indexOf replace search subStr 
    // subString splite fromCharCode slice
    var a = "qwe";
    console.log(a);    var p = a.indexOf("e");
    console.log(p);
    document.write(String.fromCharCode(72,69,76,76,79));</script>
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2. Array object

<script type="text/javascript">
        // 创建数组
        var arr1 = [1,2,3];        var arr2 = new Array(); // 空数组
        var arr3 = new Array(5); // 长度为5
        var arr4 = new Array("8"); // ["8"]
        var arr5 = new Array(4,5); // [4,5]
        console.log(arr1,arr2,arr3,arr4,arr5);        // 属性
        console.log(arr5.length);        // 方法
        // pop push 对数组的末尾添加/删除元素
        var newLength = arr5.push(6,7,8);
        arr5.pop();
        console.log(arr5, newLength);        // unshift shift  对数组首位添加/删除元素
        arr5.unshift(9);
        console.log(arr5);        var arr6 = [1,2,3,4];        // 数组反转 把数组元素的顺序反过来
        arr6.reverse();
        console.log(arr6);        // 把数组转化为字符串
        var str = arr6.join("-");
        console.log(str);        // 排序
        arr7 = [99, 45, 78, 22, 11, 1, 123];
        arr7.sort(function(a, b){
            return a - b;
        });
        console.log(arr7);        // splice(index,length, item1,item2.....itemn);
        // 用后面的item覆盖前面index和length组成的范围
        var arr8 = [11, 22, 33, 44];
        arr8.splice(2, 0, 999);
        console.log(arr8);    </script>
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3. Date object

<script type="text/javascript">
        // Date
        var date = new Date("2015-1-2");        var date2 = new Date("2015-1-1");
        console.log(date);
        console.log(date2);        // 两个日期相减得到的是时间差,单位是毫秒
        var res = date - date2;
        console.log(res/1000/3600/24 + 1);        // get 获取
        console.log(date.getFullYear());        // set 设置
    </script>
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4. Mathematical object

<script type="text/javascript">
        // Math
        // 属性
        console.log(Math.PI);        // 方法
        // 生成0-1的随机数
        Math.random();        // abs 返回绝对值
        Math.abs(-3);    </script>
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5. Regular expression

<script type="text/javascript">
        // reg = /正则部分(定义的规则)/正则属性
        // g 全局匹配 i是否区分大小写
        var reg = /test/gi
        var str = "hellotesthowareTESTyoutest";
        console.log(str.match(reg));        // \d 代表数字
        var reg2 = /\d/g;        var str2 = "wfawsefw2390480asdfas";
        console.log(str2.match(reg2));        // \w 代表单词字符 数字 字母 下划线
        var reg3 = /\w/g;        var str3 = "sgfsd234hjl_ sdfj+ \*`134212asd2( ,:a";
        console.log(str3.match(reg3));        // .匹配任意字符(除去换行符 \n)
        var reg4 = /./g;        var str4 = "4hjl_ sdfj+ \t*`1342\n12asd2( ,:a";
        console.log(str4.match(reg4));        // \s匹配空格字符 匹配空格
        var reg5 = /\s/g;
        console.log(str4.match(reg5));        // 量词
        var reg6 = /\d{1,3}/g;        var str6 = "3456787re0wr4645";
        console.log(str6.match(reg6));        // 方括号
        // 2 3 4 6里面的任何一个
        var reg7 = /[2-46{2}]/g;        var str7 = "23985734985028040";
        console.log(str7.match(reg7));        // 除去123以外的任何一个 
        var reg8 = /[^123]/g;        var str8 = "1234567890";
        console.log(str8.match(reg8));        // 小括号
        var reg9 = /3((4)|(2))/g;        var str9 = "2340250123284081";
        console.log(str9.match(reg9));        // 开头和结尾
        // ^ $
        var reg10 = /^34$/g;        var str10 = "342093434";
        console.log(str10.match(reg10));        // 11位 纯数字 1开头
        var reg11 = /^1(3[01379]|47|5[0258])\d{8}$/g;        var str11 = "13045340509";
        console.log(str11.match(reg11));        // 邮箱
        // (4-10位单词字符 开头必须是字母)@
        // @qq @163 . cn com
        var reg12 = /^[A-Z]|[a-z]\w{3,9}@(qq|163)(.com|.cn)$/g;        var str12 = "asdfsf@qq.com";
        console.log(str12.match(reg12));    </script>
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