What is the essence of const?
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.
