20个提升效率的JS简写技巧

正文 简写技巧 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; 复制代码 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]; 复制代码 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'; 复制代码 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'; 复制代码 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(); 复制代码 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]; 复制代码 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; 复制代码 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}`); 复制代码 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' + 'often just-in-time compiled, and multi-paradigm.' ); //Shorthand console.log(`JavaScript, often abbreviated as JS, is a programming language that conforms to the often just-in-time compiled, and multi-paradigm.` ); 复制代码 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 } 复制代码 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}; 复制代码 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'; 复制代码 使用repeat()方法简化重复一个字符串 //Longhand let str = ''; for(let i = 0; i { 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}; 复制代码 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 复制代码 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]); } 复制代码 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 复制代码 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} 复制代码 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] 复制代码 THE END 文章(除了代码)都是以本人自己的语言组织,且有删减 正文部分的代码,Longhand表示常规写法,Shorthand表示简写形式 以上就是本文的所有内容,如有问题欢迎留言~ 最后 如果你觉得此文对你有一丁点帮助,点个赞。或者可以加入我的开发交流群:1025263163相互学习,我们会有专业的技术答疑解惑 如果你觉得这篇文章对你有点用的话,麻烦请给我们的开源项目点点star: ​​https://gitee.com/ZhongBangKeJi/CRMEB​​不胜感激 ! PHP学习手册:https://doc.crmeb.com/ 技术交流论坛:​​https://q.crmeb.com/​​

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