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Editor to share with you how JavaScript empty and assign default values, I believe that most people do not understand, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Null and assign default value

I often see code like this in Code Review, which assigns a value to the second variable when it is determined that the variable is not null,undefined,'', otherwise it gives a default value:

If (first! = = null | | first! = = undefined | | first! = ='') {let second = first;} / / abbreviation let second = first | |'; javascript is a dynamically typed, weakly typed language based on object and event-driven, relatively secure and widely used in client-side web page development, as well as a widely used scripting language for client-side Web development. It is mainly used to add dynamic functions to HTML web pages, and now JavaScript can also be used in web servers, such as Node.js.

The above is all the contents of the article "how to determine null and assign default values by JavaScript". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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