Sharing the differences between const, var and let in js

This article mainly shares with you the differences between const, var, and let in js. I hope it can help you.

const cannot be modified and must be initialized. The variables defined by

const NAME；
Uncaught SyntaxError: Missing initializer in const declaration

const NAME = 'marain'；
NAME = 'marin2'
Uncaught SyntaxError: Missing initializer in const declaration

var can be modified. If not initialized, undefined will be output and no error will be reported.

let Block-level scope, the function is set internally, and has no effect outside the function. It can be used for ( let i = 0; )

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