What do the three dots in JavaScript mean?

This article mainly explains "what do the three points in JavaScript mean?" the content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn what the three points in JavaScript mean.

In JavaScript, there are three dots. Represents the extension operator, is a new addition in ES6, it can be in the function call / array construction, the array expression or string at the syntax level; you can also construct literal objects when the object expression is expanded in the way of "key-value".

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

We often see (...) three dots when we look at the js code. What does it mean? What's the use?

Next, I would like to share with you those things about the three points.

What does it mean?

The real name of the three dots (...) is the extension operator, which is a new addition in ES6. It can expand the array expression or string at the syntax level when the function call / array construction is made. It can also expand the object expression in the way of key-value when constructing literal objects.

The literal quantity generally refers to the concise construction of [1 name:'chuichui' 2] or {3}, and the multi-layer nested array and three points of objects are powerless.

To put it bluntly, it means to take off your clothes, whether it's curly braces ([]) or curly braces ({}). Take them all off!

/ / Array var number = [1 name:'chuichui',height:176 2 console.log 3 4 5 5 var number 6] console.log (... console.log) / / 1 2 3 4 56 man / object var man = {name:'chuichui',height:176} console.log ({... man}) / {name:'chuichui',height:176}?

It has a wide range of uses, which we can see everywhere. Here are a few common examples.

Copy replication with it / / array var arr1 = ['hello'] var arr2 = [... arr1] arr2 / / [' hello'] / / object replication var obj1 = {name:'chuichui'} var obj2 = {... arr} ob12 / / {name:'chuichui'} merge it / / array var arr1 = ['hello'] var arr2 = [' chuichui'] var mergeArr = [. Arr1,...arr2] mergeArr / / ['hello'] 'chuichui'] / / object splitting and merging var obj1 = {name:'chuichui'} var obj2 = {height:176} var mergeObj = {... obj1,...obj2} mergeObj / / {name: "chuichui", height:176} character transfer array var arr1 = [.' hello'] arr1 / / ["h", "e", "l", "l", "o"] function passes parameters to it

Can be combined with normal functions, flexible use

Function f (vMagnewPercience x repense yremenz) {} var args = [2mage3] f (1pr.. argspr 4rec. [5])

When we want to iterate the elements in the array into function parameters, use it!

Function f (xjingyjinz) {} var args = [1Magne2Magne3] f (. Args) / / the previous method f.apply (null,args); thank you for reading, the above is "what does the three points in JavaScript mean". After the study of this article, I believe you have a deeper understanding of the meaning of the three points in JavaScript, and the specific use needs to be verified by practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!