check null string in javascript

When discussing the primitive data types in Javascript, most people know the basic knowledge, from String, Number to Boolean. These primitive types are quite simple and behavior is common sense. However, this article will focus more on the unique

When discussing the raw data types in JavaScript, most people know the basics, from String,number to Boolean. These primitive types are fairly simple and behave in a common sense. However, this article will focus more on the unique original data

, native JavaScript implements string length interceptionView Code2. Native JavaScript gets the domain hostView Code3. Native JavaScript Clear spaceView Code4. Native JavaScript replaces allView Code5. Native JavaScript Escape HTML tagView Code6.

When discussing the primitive data types in JavaScript, most people know the basic knowledge, from String, Number to Boolean. These primitive types are quite simple and behavior is common sense. However, this article will focus more on the unique

This article mainly introduces the Null and Undefined primitive data types in javascript. If you need them, you can refer to the basic knowledge that most people know when discussing the primitive data types in JavaScript, from String, Number to

You can just check if the variable have a truthy value or not. That meansif( value ) {}Would evaluate to true if are not value : Null Undefined NaN Empty string ("") 0 False The above list represents all possible

We often see some data types in javascript, such as "undefined", "boolean", and "string, this article will help you learn the basic JavaScript data types, value types, and reference types. For more information, see this article, four basic data

Directory1 History 2 clarifying misunderstandings 3 basic concepts 4 features 5 different from Java 6 development toolsHistoryProbably in 1992, a company called Nombas began developing an embedded scripting language called C-minus (C-minus-minus, or

1. Type analysis :The data type in JS has 5 kinds of undefined,boolean,number,string,object, the first 4 is the original type, and the 5th type is reference.Code Copy Code code as follows: var A1; var a2 = true; var a3 = 1; var

1. Type Analysis:The data types in js include undefined, boolean, number, string, and object. The first four are original data types and the second are reference data types.Code Copy codeThe Code is as follows: var a1; Var a2 = true; Var a3 = 1; Var