javascript typeof class name

Typeof + instanceof + toString + constructor: How does one determine the javascript data type? typeofinstanceofI. typeof Variables in JS are loose (weak type) and can be used to save any type of data.Typeof can be used to detect the Data Type of a given variable. Possible return values: 1. 'undefined' --- the value is undefined; 2. 'boolean' --- the value is a bo

type, which we call a class in object-oriented languages. Now in JavaScript, we also have the definition class method, which defines function. The class is also an object, and the type of the class object is a function. As you can see, the complex type in

The typeof in JavaScript is actually very complicated. It can be used to do many things, but it also has a lot of weird performances. This article lists its usage and points out the existing problems and solutions. The premise of reading this article is that you should now know the difference between the original value and the object value. Check whether a variable exists and has a valueTypeof will return "

The typeof in JavaScript is actually very complicated. It can be used to do many things, but it also has a lot of weird performances. This article lists its usage and points out the existing problems and solutions. The premise of reading this article is that you should now know the difference between the original value and the object value. Check whether a variable exists and has a valueTypeof will return "

reference type when using the TypeOf operator, and it returns "Object" regardless of what type of object is referenced. This requires the use of instanceof to detect whether an object is an instance of another object.Generally speaking, usinginstanceof is to determine whether an instance is of a certain type. In addition, the heavier point is that instanceof can be used in an inheritance relationship to determine whether an instance belongs to its pa

in Web front-end development, we often need to judge the data type of a variable. Since ECMAScript is loosely typed, there is a need to have a means to detect the data type of a given variable--typeof is the operator responsible for providing this convenient information. Using the typeof operator on a value may return one of the following strings: "Undefined"-if the value is not defined "boolean"-if the va

Using the typeof operator on a value may return one of the following strings:"Undefined"--if this value is not defined"Boolean"--if this value is a Boolean value"String"--if this value is a string"Number"--if this is a numeric value"Object"--if this is an object or null"Function"--if this value is a function The return values of the commonly used typeof operators include number, String, Boolean, Undefined,

JavaScript is designed. But the problem is that if you call typeof, you should exactly return the type of the variable, whether it was created directly with a value or a constructor of a type, otherwise! What am I going to do with you? So for: The code is as follows: var a = 1; var B = new number (1); The type of a and B variables is exactly what the number is supposed to be. The exact type informat

course in the book, because that's how JavaScript is designed. But! The problem is that if you call typeof, you should exactly return the type of the variable, whether it was created directly with a value or a constructor of a type, otherwise! What else am I doing with you? So for: Copy Code code as follows: var a = 1; var B = new number (1); The type of a and B variables is exac

To set the style of an element by using the ClassName property: The id= "P1" element is added to the "class name one" style by classname. When you click the "Add Style" button, the first paragraph of text adds a style. The id= "P2" element is modified by classname to the style "class name is two". When y

typeof operatorThe typeof operator (together with instanceof) may be the biggest design flaw in JavaScript,Because it is almost impossible to get the desired results from them.Although Instanceof still has a few application scenarios, typeof has only one practical application: The actual application is used to detect w

In front-end Web development, we often need to determine the Data Type of variables. Since ECMAScript is loose, there is a need to detect the Data Type of a given variable-typeof is the operator responsible for providing this convenient information. Using the typeof operator for a value may return one of the following strings: "Undefined" -- if this value is not defined "Boolean" -- if this value is a boole

This article will share with you the function of adding and removing javascript class names. For more information about how to add and remove javascript class names, see this article. Method 1: Use the className attribute; Method 2: Use the classList API; // Function reg (name