In this article we explore the void keyword in JavaScript. The void operator evaluates an expression and returns undefined. The void keywordThe void operator evaluates any given expression and then returns unde
写在前面 ECMA-262定义了ECMAScript所支持的关键字(keyword),关键字不能用作ECMAScript程序的标识符(Indetifiers)。ECMA-262标准定义了以下关键字: breakdoinstanceoftypeofcaseelsenewvarcatchfinallyreturnvoidcontinueforswitchwhiledebuggerfunctionthiswithdefaultifthrowdeleteintry void 根据ECMA-262定义,void是javascrip...
JavaScript - Void 关键字 void 是JavaScript中一个重要的关键字,可用作一元运算符,出现在其单个操作数之前,该操作数可以是任何类型。该运算符指定要评估的表达式,但不返回值。 语法 void 的语法可以是以下两种之一 -
译文首发于众成翻译:http://www.zcfy.cc/article/2620 原文链接:http://cmichel.io/javascript-void-keyword/看这是啥语言? void function foo() { // ... } 是的,JavaScript,从文章标题里就知道了。最近在 c…
JavaScript 中 void 是一个重要的关键字。它可以用作一个一元运算符,此时它会出现在一个操作数之前,这个操作数可以是任意类型的。这个操作符指定要计算一个表达式但是不返回值。它的语法可能是下列之一: <!-- void func() javascript:void func() or: void(func()) javascript:void(func()) //--> 例...
1. We expect the res to be [1, 2], but we got 2, this is because 'push' method return the length of the array as a result. To solve the problem we can use 'void' keyword, it will execute the expression and return undefined as a result, for example: ...
package java.lang; /** * The {@code Void} class is an uninstantiable placeholder class to hold a *...reference to the {@code Class} object representing the Java keyword * void...* * @author unascribed * @since JDK1.1 */ public final class Void { /** * The {@code...@Suppress...
package java.lang; /** * The {@code Void} class is an uninstantiable placeholder class to hold a *...reference to the {@code Class} object representing the Java keyword * void...* * @author unascribed * @since JDK1.1 */ public final class Void { /** * The {@code...@Suppress...
Using anIIFE, the void can be used for forcing the function keyword to be treated as an expression rather than a declaration. void function hello() { var msg = function () {console.log("Welcome back!!")}; msg(); }();// Welcome back!!
If you ask why do you need a special keyword just to return undefined instead of just returningundefined: the reason is that before ES5 you could actually name a global variableundefined, like so:var undefined = "hello"orvar undefined = 23, and most browsers would accept it; the identifier...