How do you use a Select Case like in JavaScript?

Switch statement Language Reference Description When the value of the specified expression matches a label, the corresponding one or more statements are executed. Grammar switch (expression) { case label: statementlist case

JavaScript very personalized Picture Show magnification display effect


Tip: You can modify some of the code before running JavaScript very personalized Picture Show magnification display effect very personalized picture display effect (10) and Between--> and --> & lt;/span> &L T;span >

How to use document.getElementById in JavaScript

Changing HTML Properties To change the attributes of an HTML element, use this syntax: document.getElementById (ID). attribute=new valueThis example changes the SRC attribute of the element: Change HTML Style To change the style of HTML elements,

How to use JavaScript to implement copy, Paste function

Copies can be used: objects. createTextRange (). ExecCommand ("copy") command, you can use: Window.clipboardData.setData ("text", source of content) Here the source of the content such as to get text box ID for y text copy to the Clipboard, here

Learning notes for callback functions in JavaScript

callback function Principle: I'm leaving now, I'll let you know.This is an asynchronous process, "I go" in the process (function execution), "You" can do anything, "to" (function completed) "Notify You" (callback) after the process Example

Examples of JavaScript operation arrays and descriptions of functions

1): Join () Method:Converts all elements of an array into strings.Like what: var a = [1,2,3];var s = a.join (); Output s==1,2,3Of course, you can also specify a separator;Like \s = A.join (",");In contrast to String.Split (), split () splits a

JavaScript Number Format Function detailed


JavaScript provides part of the number format method, but not perfect, you can look at the use of the number object, which provides some formatted output of numbers, several functions are as follows: Toexponential ([fractiondigits]): Returns the

Working notes for JavaScript asynchronous programming

JavaScript's execution engine is single-threaded, and is normally the mode of synchronous programming, where the program executes sequentially from top to bottom in order of code. As long as one task takes a long time, the subsequent tasks must be

JS detects whether a function is a JavaScript native function

In my development work, I often encounter situations where it is necessary to determine whether a function is a JavaScript native function, and it is sometimes a necessity to know if the function is provided by the browser itself or by a third party,

JavaScript determines whether a function exists

Judging method The code is as follows Copy Code typeof (Test) = = "function"Boolean (Window.loginok instanceof Function)Boolean (window.parent.loginOk instanceof function)//judging functions in the parent page

JavaScript determines whether the program code is empty

Whether the variable is empty The following is the result of the IF (TMP) {} decision: The code is as follows Copy Code if (TMP) if (tmp!=null)//false//false when TMP is

A summary of JavaScript array append methods

I used the Arr.concat (arr2) method to append an array, as shown in the following example The code is as follows Copy Code JS array elements to add and delete has been more puzzled, today finally found the

JavaScript implementation does not upload pictures direct local preview

Principle is divided into two steps: when the upload image input is triggered and select a local image to upload the image of the object URL (object URL); Assign the object URL to the pre-written img tag src attribute can display the picture. Here

Summary of regular expressions in JavaScript

Ways to define regular expressionsThere are two ways to define a regular expression: the constructor definition and the regular expression direct quantity definition. For example: The code is as follows Copy Code var reg1

JavaScript implements drag-and-drop effects on elements (1/2)

The drag of a DOM node is a simple JavaScript effect, often called a drag-and-drop, that is, Drag-and-drop. Drag and drop mainly involves three processes: Click on the object you want to drag and drop to record the mouse relative to the drag

A detailed explanation of JavaScript variables (local/global)

Local JavaScript variable A variable declared inside a JavaScript function (using VAR) is a local variable, so it can only be accessed within the function. (The scope of the variable is local).You can use local variables with the same name in

JavaScript determines whether the specified string is a valid number

================================================================================Function Summary: Check whether the specified string is a valid numberAs a person: Peter JinAs own: 2010-04-23============================================================

JavaScript Split Function Example tutorial


JavaScript Tutorial Split Function Instance Tutorial

JavaScript Ondomready executes after the DOM tree is loaded

(function () {var isready=false;//to determine if the Ondomready method has been executedvar readylist= [];//The method that needs to be executed is in this array first.var timer;//timer handleReady=function (FN) {if (IsReady)

The judgment of JavaScript function types

When judging the type of a function, we use the TypeOf method, such as: function fn () { } alert (typeof fn) //The result is "function".   However, the method does not work as we think in some browsers. 1,

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