Take you two minutes to understand the value transfer method of JS

During this period, I have done some full-stack things and gained some learning and understanding of JS. This article is mainly a summary of the value-passing method of JS.

We generally say that JavaScript is passed by value, but from a certain perspective, it can also be said that it is passed by reference. Let’s sort it out below.

We generally divide the value-passing of JS into two types. When the parameters passed are primitive types, it is completely passed-by-value.

When an object is passed, a clone of the reference to the object is passed, and the value is still passed.

The following are traditional types:

Includes 5 data types. There is no concept of class in javaScript, only one Pseudo-type.

Reference type:

How to understand?
When we pass a value, the operation on the value will not affect the original data.

When we share the method: the attribute control of the object (a. attribute name) can operate to the original value, but the direct reading and writing of the object (a=1) cannot contact the original object. .

var obj = {    value: 1};
function foo(o) {
    o.value = 2;
    console.log(o.value); //2  --赋值}
foo(obj);
console.log(obj.value) // 2  --值被改变var obj = {    value: 1};
function foo(o) {
    o = 2;
    console.log(o); //2    --修改的是o}
foo(obj);
console.log(obj.value) // 1 --没有影响

The usual way to compare member types:

Methods, etc. all belong to this category. This is why we use var to define methods that can be called. Reason for execution.

Thank you for reading, I hope you will benefit a lot

This article is reproduced from: https://blog.csdn.net/zzg19950824/article/details/80395287

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