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This article mainly shows you "how to determine whether JavaScript contains a value", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "how to determine whether JavaScript contains value" this article.

Determine whether it contains a value

1. The ultimate piece

IndexOf (4) / / false (4) / / indexOf (4) /-1 return undefined if there is no value in the array ((item) = > item===3) / / 3 if there is no value in the array. FindIndex ((item) = > item===3) / 1 if there is no value in the array

Includes (), find (), findIndex () are the api of ES6

two。 The beginning

[1 return item===3 2] .some (item= > {return item===3}) / / true if it does not include all the contents of the article "how to determine whether or not JavaScript contains a value", 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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