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This article mainly introduces the relevant knowledge of what the essence of const is, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value. I believe you will gain something after reading the essence of this const. Let's take a look at it.

Not a real constant.

The essence of const: the variable defined by const is not constant, not immutable, it defines a constant that refers to a value. Objects or arrays defined using const are actually mutable. The following code does not report an error:

Case study

/ / create a constant object

Const car = {type: "Fiat", model: "500,500", color: "white"}

/ / modify attributes:

Car.color = "red"

/ / add attributes

Car.owner = "Johnson"

But we cannot reassign constant objects:

Case study

Const car = {type: "Fiat", model: "500,500", color: "white"}

Car = {type: "Volvo", model: "EX60", color: "red"}; / / error

The following example modifies the constant array:

Case study

/ / create a constant array

Const cars = ["Saab", "Volvo", "BMW"]

/ / modify elements

Cars [0] = "Toyota"

/ / add elements

Cars.push ("Audi")

But we cannot reassign the constant array:

Case study

Const cars = ["Saab", "Volvo", "BMW"]

Cars = ["Toyota", "Volvo", "Audi"]; / / error

This is the end of the article on "what is the essence of const". Thank you for reading! I believe you all have a certain understanding of "what is the essence of const". If you want to learn more, you are welcome to follow the industry information channel.

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