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20个JS简写技巧提升工作效率

2022-01-08 04:07 766 查看 https://www.geek-share.com/det
目录
  • 使用for in和for of来简化普通for循环
    • 简化获取字符串中的某个字符
      • 移除对象属性
        • 使用arr.filter(Boolean)过滤掉数组成员的值falsey
          • 前言:

            最近看了一些简化JS代码的文章,其中有一篇觉得还不错,但是是英文的,也看了一些中文翻译,一个是一字一句翻译太生硬,没有变成自己的东西,另外就是后面作者有新增没有及时更新,于是我按照自己的语言翻译整理成此文,本文特点以言简意赅为主

            当同时声明多个变量时,可简写成一行

            //Longhand
            let x;
            let y = 20;
            
            //Shorthand
            let x, y = 20;

            利用解构,可为多个变量同时赋值

            //Longhand
            let a, b, c;
            
            a = 5;
            b = 8;
            c = 12;
            
            //Shorthand
            let [a, b, c] = [5, 8, 12];

            巧用三元运算符简化if else

            //Longhand
            let marks = 26;
            let result;
            if (marks >= 30) {
            result = 'Pass';
            } else {
            result = 'Fail';
            }
            
            //Shorthand
            let result = marks >= 30 ? 'Pass' : 'Fail';

            使用||运算符给变量指定默认值

            本质是利用了||运算符的特点,当前面的表达式的结果转成布尔值为false时,则值为后面表达式的结果

            //Longhand
            let imagePath;
            
            let path = getImagePath();
            
            if (path !== null && path !== undefined && path !== '') {
            imagePath = path;
            } else {
            imagePath = 'default.jpg';
            }
            
            //Shorthand
            let imagePath = getImagePath() || 'default.jpg';

            使用&&运算符简化if语句

            例如某个函数在某个条件为真时才调用,可简写

            //Longhand
            if (isLoggedin) {
            goToHomepage();
            }
            
            //Shorthand
            isLoggedin && goToHomepage();

            使用解构交换两个变量的值

            let x = 'Hello', y = 55;
            
            //Longhand
            const temp = x;
            x = y;
            y = temp;
            
            //Shorthand
            [x, y] = [y, x];

            适用箭头函数简化函数

            //Longhand
            function add(num1, num2) {
            return num1 + num2;
            }
            
            //Shorthand
            const add = (num1, num2) => num1 + num2;

            需要注意箭头函数和普通函数的区别

            使用字符串模板简化代码

            使用模板字符串代替原始的字符串拼接

            //Longhand
            console.log('You got a missed call from ' + number + ' at ' + time);
            
            //Shorthand
            console.log(`You got a missed call from ${number} at ${time}`);

            多行字符串也可使用字符串模板简化

            //Longhand
            console.log('JavaScript, often abbreviated as JS, is a\n' +
            'programming language that conforms to the \n' +
            'ECMAScript specification. JavaScript is high-level,\n' +
            'often just-in-time compiled, and multi-paradigm.'
            );
            
            //Shorthand
            console.log(`JavaScript, often abbreviated as JS, is a
            programming language that conforms to the
            ECMAScript specification. JavaScript is high-level,
            often just-in-time compiled, and multi-paradigm.`
            );

            对于多值匹配,可将所有值放在数组中,通过数组方法来简写

            //Longhand
            if (value === 1 || value === 'one' || value === 2 || value === 'two') {
            // Execute some code
            }
            
            // Shorthand 1
            if ([1, 'one', 2, 'two'].indexOf(value) >= 0) {
            // Execute some code
            }
            
            // Shorthand 2
            if ([1, 'one', 2, 'two'].includes(value)) {
            // Execute some code
            }

            巧用ES6对象的简洁语法

            例如:当属性名和变量名相同时,可直接缩写为一个

            let firstname = 'Amitav';
            let lastname = 'Mishra';
            
            //Longhand
            let obj = {firstname: firstname, lastname: lastname};
            
            //Shorthand
            let obj = {firstname, lastname};

            使用一元运算符简化字符串转数字

            //Longhand
            let total = parseInt('453');
            let average = parseFloat('42.6');
            
            //Shorthand
            let total = +'453';
            let average = +'42.6';

            使用repeat()方法简化重复一个字符串

            //Longhand
            let str = '';
            for(let i = 0; i < 5; i ++) {
            str += 'Hello ';
            }
            console.log(str); // Hello Hello Hello Hello Hello
            
            // Shorthand
            'Hello '.repeat(5);
            
            // 想跟你说100声抱歉!
            'sorry\n'.repeat(100);

            使用双星号代替Math.pow()

            //Longhand
            const power = Math.pow(4, 3); // 64
            
            // Shorthand
            const power = 4**3; // 64

            使用双波浪线运算符(~~)代替Math.floor()

            //Longhand
            const floor = Math.floor(6.8); // 6
            
            // Shorthand
            const floor = ~~6.8; // 6

            需要注意,~~仅适用于小于2147483647的数字

            巧用扩展操作符(...)简化代码

            简化数组合并

            let arr1 = [20, 30];
            
            //Longhand
            let arr2 = arr1.concat([60, 80]); // [20, 30, 60, 80]
            
            //Shorthand
            let arr2 = [...arr1, 60, 80]; // [20, 30, 60, 80]

            单层对象的拷贝

            let obj = {x: 20, y: {z: 30}};
            
            //Longhand
            const makeDeepClone = (obj) => {
            let newObject = {};
            Object.keys(obj).map(key => {
            if(typeof obj[key] === 'object'){
            newObject[key] = makeDeepClone(obj[key]);
            } else {
            newObject[key] = obj[key];
            }
            });
            
            return newObject;
            }
            
            const cloneObj = makeDeepClone(obj);
            
            //Shorthand
            const cloneObj = JSON.parse(JSON.stringify(obj));
            
            //Shorthand for single level object
            let obj = {x: 20, y: 'hello'};
            const cloneObj = {...obj};

            寻找数组中的最大和最小值

            // Shorthand
            const arr = [2, 8, 15, 4];
            Math.max(...arr); // 15
            Math.min(...arr); // 2

            使用for in和for of来简化普通for循环

            let arr = [10, 20, 30, 40];
            
            //Longhand
            for (let i = 0; i < arr.length; i++) {
            console.log(arr[i]);
            }
            
            //Shorthand
            //for of loop
            for (const val of arr) {
            console.log(val);
            }
            
            //for in loop
            for (const index in arr) {
            console.log(arr[index]);
            }

            简化获取字符串中的某个字符

            let str = 'jscurious.com';
            
            //Longhand
            str.charAt(2); // c
            
            //Shorthand
            str[2]; // c

            移除对象属性

            let obj = {x: 45, y: 72, z: 68, p: 98};
            
            // Longhand
            delete obj.x;
            delete obj.p;
            console.log(obj); // {y: 72, z: 68}
            
            // Shorthand
            let {x, p, ...newObj} = obj;
            console.log(newObj); // {y: 72, z: 68}

            使用arr.filter(Boolean)过滤掉数组成员的值falsey

            let arr = [12, null, 0, 'xyz', null, -25, NaN, '', undefined, 0.5, false];
            
            //Longhand
            let filterArray = arr.filter(function(value) {
            if(value) return value;
            });
            // filterArray = [12, "xyz", -25, 0.5]
            
            // Shorthand
            let filterArray = arr.filter(Boolean);
            // filterArray = [12, "xyz", -25, 0.5]

            到此这篇关于20个JS简写技巧提升工作效率的文章就介绍到这了,更多相关JS简写技巧内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!

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