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This article mainly shows you "how to use double question mark grammar in JavaScript". The content is simple and clear. I hope it can help you solve your doubts. Let the editor lead you to study and learn this article "how to use double question mark grammar in JavaScript".

Double question mark grammar

Const height = 0; console.log (height | | 100); / / 100 console.log (height? 100); / / 0

This? It means, if? The value on the left is null or undefined, so the value on the right is returned.

The characteristic of JavaScript 1.JavaScript is mainly used to add interactive behavior to HTML pages. 2.JavaScript can be embedded directly into HTML pages, but writing as a separate js file facilitates the separation of structure and behavior. 3.JavaScript has cross-platform features and can run on multiple platforms with the support of most browsers.

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