Detailed explanation of JS native objects and regular expressions

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>

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>

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>

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>

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>

The above is the detailed content of Detailed explanation of JS native objects and regular expressions. For more information, please follow other related articles on the PHP Chinese website!