js内置对象-优快云博客

本文链接：https://blog.youkuaiyun.com/Jsjendndn/article/details/145949932
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    <script>
        //Math
        console.log(Math.PI);
        var num1 = -1.1
        var num2 = 1.6
        console.log(Math.abs(num1));
        console.log(Math.floor(num1));
        console.log(Math.ceil(num1));
        console.log(Math.round(num1));
        var arr = [1, 6, 8, 10, 23, 12]
        console.log(Math.max(...arr));
        console.log(Math.min(1, 6, 8, 10, 23, 12));
        console.log(Math.random());
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log(Math.floor(Math.random() * 10) + 1);
        console.log('------------------');
        //Date

        //当前时间
        var date = new Date()
        console.log(date);
        //指定时间
        var double11 = new Date('2025-11-11 00:00:00')
        console.log(double11);
        var zero = new Date(0)
        var sss = new Date(1666443020)
        console.log(zero);
        console.log(sss);
        console.log(date.getDate());//返回这一月的哪一天
        console.log(date.getFullYear());
        console.log(date.getMonth());
        console.log(date.getDay());//返回星期（0是星期天）
        console.log(date.getHours());
        console.log(date.getMinutes());
        console.log(date.getSeconds());
        console.log(date.getTime());//距标准时间的ms数

        //string
        console.log('------------------');

        var str1 = 'Hello'
        var str2 = new String("Hello")
        console.log(str1.charAt(0));
        console.log(str2.charAt(0));
        console.log(str1);
        console.log(str2);
        console.log(str1.indexOf('H'));
        console.log(str1.lastIndexOf('l'));
        console.log(str1.includes("a"));
        console.log(str1.includes("h"));
        console.log(str1.includes("H"));
        var str3 = "nbcccnbcccnbccc"
        var str4 = str3.replace("nb", "123")
        console.log(str4);

        while (str3.includes("nb")) {
            str3 = str3.replace("nb", "123")
        }
        console.log(str3);
        var str5 = "11-12-31-56"
        console.log(str5.split("-"));
        var str6 = "HelloWorld"
        console.log(str6.substring(0, 3));//选出中间，左闭右开
        console.log(str6.substr(0, 6));//从0开始，摘出六个

        var s1 = "HE"
        var s2 = "LL"
        var s3 = "O"
        var sss = [s1, s2, s3]
        console.log(sss.join(''));

        //Array
        console.log('------------------');
        var arr = new Array()
        arr.push("a")
        console.log(arr);

        var arr2 = ['a', 'b', 'c']
        console.log(arr2);
        arr2.push('d')//末尾添加
        console.log(arr2);
        arr2.unshift('e')//首位添加
        console.log(arr2);
        var del = arr2.pop()//删除末尾,并返回
        console.log(del);
        console.log(arr2);
        console.log(arr2.sort());
        console.log(arr2.reverse());
        //indexOf,lastIndexOf,join
        var arr3 = ["李四", "王五"]
        arr3.forEach(function (value, index) {
            console.log(value);
            console.log(index);

        })

        var person = {
            name: '张三',
            age: 18
        }
        arr3.forEach(function (value, index) {
            console.log(value);
            console.log(index);
            console.log(this.name);
        }, person)//this指向person，如果未说明，默认指向window

        var arr4 = [1, 2, 3, 4, 5, 6]
        arr4.splice(0, 2, 1, 8, 8, 6)//从0开始，删除2个，再把剩下的加进去
        console.log(arr4);
        console.log(arr4.concat(arr3));
        console.log(arr4.slice(1, 3));//切割出来，左闭右开

    </script>

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