difference between undefined and not defined in javascript

A conceptual explanation:undefined is one of the five original classes defined in the JavaScript language, in other words, undefined is not a program error, but a value allowed by the program. not defined is a bug that JavaScript bursts when it runs

Before the cloud-dwelling community sent a similar articleJavaScript null and undefined difference analysisJavaScript undefined,null type and nan value differenceLet's talk about undefined:The variables in JavaScript are weakly typed (I don't need

Differences between undefined and not defined in javascript This article mainly introduces the differences between undefined and not defined in javascript. For more information, see The study found that there is a big difference between the two. I

Here is a collection of JS in the null and undefined two hints of the difference between analysis, for each beginner should have no small use OH. Generally known:Null = = undefinedBut:Null!== undefinedSo what's the difference between the

A bad time to answer, especially undefined, because this involves the realization of the principle of undefined. So, after thinking carefully, write down this article, please heroes to shoot bricks. Total known: null = = undefined However: null!==

Similar articles have not been posted before.Difference between JavaScript null and undefined JavaScript Undefined, difference between the Null type and the NaN Value Let's talk about undefined:The variables in Javascript are of a weak type (I don't

It is hard to answer at a time, especially undefined, because it involves the implementation principle of undefined. So, after thinking about it, write down this article. Please take a look.Total offices: null = undefinedBut: null! = UndefinedSo

It is hard to answer at a time, especially undefined, because it involves the implementation principle of undefined. So, after thinking about it, write down this article. Please take a look.Total offices: null = undefinedBut: null! = UndefinedSo

Most computer languages have and have only one value that denotes "none", such as the nil of the None,ruby language of the Null,python language of the C language Null,java language. Oddly enough, the JavaScript language actually has two values that

In JavaScript development, I was asked: What is the difference between null and undefined? It is hard to answer at a time, especially undefined, because it involves the implementation principle of undefined. Total offices: null = undefined But: