Shulou(Shulou.com)06/01 Report--

This article focuses on "JavaScript cycle scope case analysis", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor to take you to learn the "JavaScript cycle scope instance analysis" bar!

Cyclic scope

Use var in a loop:

Example

Var I = 7

For (var I = 0; I < 10; iTunes +) {

/ / some statements

}

/ / here, I is 10

Use let in a loop:

Example

Let I = 7

For (let I = 0; I < 10; iTunes +) {

/ / some statements

}

/ / here I is 7

In the first example, the variables used in the loop use var to redeclare variables outside the loop.

In the second example, the variables used in the loop use let and do not redeclare variables outside the loop.

If you declare the variable I with let in the loop, it is only within the loop that the variable I is visible.

Function scope

When declaring variables within a function, using var is very similar to let.

They all have function scope:

Function myFunction () {

Var carName = "porsche"; / / function scope

}

Function myFunction () {

Let carName = "porsche"; / / function scope

}

Global scope

If you declare a declaration outside a block, then var and let are similar.

They all have a global scope:

Var x = 10; / / Global scope

Let y = 6; / / Global scope

At this point, I believe you have a deeper understanding of "JavaScript loop scope instance analysis". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.