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This article mainly introduces JavaScript how to use the chain judgment operator, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.

Chain judgment operator'?'

Suppose there is an object

Const student = {name: {firstName: 'Joe'}}

We want to do something in the presence of firstname, and we have to check layer by layer.

If (student & & student.name & & student.name.firstName) {console.log ('student First name exists')}

The chain judgment operator will stop and return undefined when a value cannot be obtained at a certain layer.

If (student?.name?.firstName) {console.log ('student First name exists')} Thank you for reading this article carefully. I hope the article "how to use the chain judgment operator in JavaScript" shared by the editor will be helpful to you. At the same time, I hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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