JavaScript and provincial level two Cascade menu

Tip: You can modify some of the code before running This JavaScript allows users to select a region and second place in the world, and then in the region of the country, in particular the Pull-down menu changes select region Asia

Examples of three-mesh operations in JavaScript

In JavaScript, in addition to if ... else and switch statements, there is also a unique three-mesh operator? ...:, also can be used for simple selection structure. Grammar: Conditions? STATEMENTA:STATEMENTB; The above statement, first judge the

Examples of JavaScript function overloading

JS itself does not support overloading, because the method call is only related to the method name, regardless of the number and type of parameters, it is this feature, we can implement the overload in a simpler way.We can use array arguments to get

Detailed JavaScript high performance template engine arttemplate principle

As the web grows, front-end applications become more complex, and JavaScript (Node.js), based on back-end, is starting to emerge, while JavaScript is being placed in greater anticipation, while JavaScript MVC is becoming popular. JavaScript template

46 JavaScript code snippets commonly used in development

45 useful JavaScript tips, tips and best practices Translator: Dwqs In this article, I'll share some of the techniques, tips, and best practices that are commonly used in JavaScript. Whether JavaScript developers are using the browser/engine or

JavaScript check refers to the example of the region text

Example function SelectAll (ID) {var h = document, I = H.getelementbyid (id), D, G;if (H.body.createtextrange) {D = Document.body.createTextRange ();D.movetoelementtext (i);D.select ()} else {if (window.getselection) {g = window.getselection ();D =

Examples of JavaScript timer usage

There are two functions in JavaScript that can implement the functions of the "timer" settimeout and setinterval, the parameters of the two functions are the same, but the meaning of the representative is different. For example settimeout (' Test ()

The difference between null and undefined in JavaScript

Null and undefined are two types of JavaScript, and the values of the types are as follows: type value Null Only one value is null Undefined Only one value undefined Null indicates

JavaScript to remove whitespace various methods summary

Method One: Personally think the best way. Using regular expressions, this is the core principle.Second, this method uses the prototype properties of JavaScript In fact, you do not use this property can be implemented using the function. But this

A summary of various methods of JavaScript array ordering

Order of singular groups Sort () function The sort method of an array object can rearrange the array elements in a certain order. Usually, they are arranged in the order of subtitles. When sort () is used, the comparison function is executed each

JavaScript array, Object object for loop efficiency comparison

The original small air (hill) said to me, use object objects less than the array object, because the efficiency of the object is higher, and today just write a JS encountered an array or object with the problem, so simply write the test page.

JavaScript for While loop usage method

For Loops a section of code to a specified number of times While Loops execute code when the specified condition is true For loop Use a For loop when the number of times the script is run is determined. Grammar: for (variable = start value;

JavaScript validation upload picture type function detailed

The foreground call is as follows The code is as follows Copy Code onclientclick= "Return Fuccheckjpgandgif" (Form1. File1.value); " --where File1 is the upload file control Function code: The code

JavaScript common Operations Array functions

Array manipulation functions Join (delimiter) to use delimiters (delimiter) for each element in the array as a stringConcat (Array1, array2, ...) Merges the array, does not affect the original array, but returns the merged new arrayPop () deletes

Usage of JavaScript logical runs

Comparison and logical operators are used to test true or false.Comparison operatorsComparison operators are used in logical statements to determine whether a variable or value is equal InstanceLogic and and Conditions and operators

Use of JavaScript typeof () and operator usage

typeof operatorReturns a string that is used to represent the data type of an expression. typeof[() expression[]]; The expression parameter is any expression that needs to find the type information. DescriptionThe typeof operator returns the type

JavaScript new constructor properties and prototype (1/3)

When a Web page effects object is generated: such as: function BB (a) {This.a= "KKK"} var b=new bb ();At this time B is the object has the BB attribute prototype to the prototype object;The prototype object has a constructor attribute pointing to

JavaScript indexof syntax and instance usage tutorials

Definitions and usage The indexof () method returns the location of the first occurrence of a specified string value in a string. Grammar Stringobject.indexof (Searchvalue,fromindex) Parameters Description

A tutorial on how to implement the user clicks count by javascript

In the micro-letter to do a promotional campaign, the page amounted to three buttons, the need to count the number of clicks, the relevant statistics on the PC is "Baidu statistics", because the H5 activity page timeliness and other reasons, and did

JavaScript dom Getting Started tutorial (1/3)

The code is as follows Copy Code document.getElementById (' intro '). Style.color = ' #FF0000 '; In order to understand the functionality of this API, it is easy to understand that by looking at it from one step to the next:

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