Case Analysis of JavaScript Declaration Promotion

This article mainly explains "JavaScript declaration promotion example analysis", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let Xiaobian take you to learn "JavaScript declaration promotion example analysis"!

JavaScript Statement Elevated

In JavaScript, declarations of functions and variables are promoted to the top of the function.

In JavaScript, variables can be declared after use, that is, variables can be declared after use.

The following two examples will get the same result:

Example 1

x = 5; //variable x is set to 5

elem = document.getElementById("demo"); //Find element

elem[xss_clean] = x; //Show x in element

var x; //Declaration x

Example 2

var x; //Declaration x

x = 5; //variable x is set to 5

elem = document.getElementById("demo"); //Find element

elem[xss_clean] = x; //Show x in element

To understand the above example, you need to understand "hoisting."

Declarations promotion: Function declarations and variable declarations are always quietly "promoted" by the interpreter to the top of the method body.

At this point, I believe that everyone has a deeper understanding of "JavaScript declaration promotion instance analysis", so let's actually operate it! Here is the website, more related content can enter the relevant channels for inquiry, pay attention to us, continue to learn!