The if block may be followed by an optional else statement. The instruction block associated with the else block is executed if the expression evaluates to false.Example: Simple ifelsevar num = 12; if (num % 2 == 0) { console.log("Even"); } else { console.log("Odd"); } ...
对象式环境记录:对象环境记录用于定义ECMAScript元素的效果,例如WithStatement,它将标识符绑定与某些对象的属性关联起来。 let/const基本使用 ◼ 在ES5中我们声明变量都是使用的var关键字,从ES6开始新增了两个关键字可以声明变量:let、constlet、const在其他编程语言中都是有的,所以也并不是新鲜的关键字; ...
if ladder/nested if statements The elseif ladder is useful to test multiple conditions. Following is the syntax of the same. 4 switchcase Statement The switch statement evaluates an expression, matches the expressions value to a case clause and executes the statements associated with that case...
AI代码解释 functionaa(flag){if(flag){vartest='hello man'}console.log(test)}aa(true); 以上的代码实际上是: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 functionaa(flag){vartest// 变量提升if(flag){test='hello man'}console.log(test)}aa(true); 所以不用关心bool是否为true or false。...
// Expression bodies 表达式体varodds = evens.map(v=>v +1);/*v=>v+1相当于function(v){return v+1;}*/varnums = evens.map((v, i) =>v + i);varpairs = evens.map(v=>({even: v,odd: v +1}));// Statement bodies 声明体nums.forEach(v=>{if(v %5===0) ...
var nums = evens.map((v, i) => v + i); var pairs = evens.map(v => ({even: v, odd: v + 1})); // Statement bodies nums.forEach(v => { if (v % 5 === 0) fives.push(v); }); // Lexical this var bob = { ...
对象式环境记录:对象环境记录用于定义ECMAScript元素的效果,例如WithStatement,它将标识符绑定与某些对象的属性关联起来 4. 内存图的表示 function foo() { console.log("foo function") } var message = "Hello World" foo() 1. 2. 3. 4. 5. 6. 7. 2. let、const的使用 1. 基础的使用 在ES5中我们...
var nums = evens.map((v, i) => v + i); // Statement bodies nums.forEach(v => { if (v % 5 === 0) fives.push(v); }); // Lexical this var bob = { _name: "Bob", _friends: [], printFriends() { this._friends.forEach(f => ...
if(name === "Peter"){ let hello = "Hello Peter"; } else { let hello = "Hi"; } console.log(hello); 上述代码同样会抛出 ReferenceError: hello is not defined 异常,因为 hello 只能够在闭合的块作用域中进行访问,我们可以进行如下修改: ...
Within a code block, comments to the right of aconsole.log()statement indicate the output you'll see in the browser or Node.js console when the code is executed, for example: 在一个代码块中,console.log ()语句右侧的注释指示代码执行时在浏览器或 Node.js 控制台中看到的输出,例如: ...