The Options action Method Collection _ form effects in JavaScript select tags

JavaScript Operations Select tags in the options collection Let's take a look at the options set in the following ways: The Options.add (option) method adds an option object to the collection; The Options.remove (index) method removes the specified

JavaScript textarea dynamic display of remaining characters _ form effects

limitations of remaining words remaining characters:

JavaScript type file Input button function Research _ form Effects

Like This is a cool video upload selection, it is through the Flash method to achieve the display of non-video class files. Flash to this effect is generally as described here Copy Code code as

JavaScript Form Date Selection Effect _ Time Date

Agenda   &L T;p align=center>     year    month   & LT;TD colspan= "3" align= "center" > today: ;/div> [Ctrl + A All SELECT Note: If the need to introduce external JS need to refresh to perform]

10 JavaScript experience per day (Ii.) basics

1. Non-numeric type conversion value Number()When using transformations: Undefined will be Nan. If the string starts with 0, the browser ignores the leading 0 and does not convert according to the octal system If the string starts at

JavaScript prototype in the use of detailed knowledge _ basics

First look at the following code: function Machine (Ecode, horsepower) { this.ecode = Ecode; This.horsepower = horsepower; } function ShowMe () { alert ( + "" + This.ecode + "" + This.horsepower); } var machine = new Machine

The iterative and merging methods in JavaScript-basic knowledge

Iterative methods Iterative methods are particularly important in JavaScript, and in many cases there are actual requirements, JavaScript provides 5 iterative methods for us to operate, respectively: Every () each item in the array uses the given

Deep parsing of arguments objects in JavaScript basics

Arguments definition All functions have a arguments object that stores the arguments it actually receives, rather than the list of parameters defined when the function declaration is used. It is not an array but resembles an array, with an

Commonplace JavaScript Array Usage _ basics

Introduction to JavaScript arrays Arrays in JavaScript are different from arrays in other languages, mainly in: The items stored in an array can be of different types of data The size of the array is dynamic and can be changed dynamically when

JavaScript Number Object Introduction _ Basics

Number object is a digit, and its construction method: Copy Code code as follows: var num = 10; var num = new number ();//num = = 0 var num = new number (value); Where value is a numeric value or a quantity that can be

JavaScript Boolean type Object _ Basics

The Boolean object is similar to the Boolean package class in Java, and it has two values: True and False 1. Create a Boolean object Copy Code code as follows: var boo = new Boolean ()//The Boo is not assigned at this time, but its

JavaScript Array Object Detail _ basics

1. Create an Array object method: --->var arr = [Element0, Element1, ..., elementn];//simple definition method Copy Code code as follows: var arr = [1,2,3] Now you know Copy Code code as follows: Arr[0] = = 1; ARR[

Basic knowledge of JavaScript basics _

1, var msg;//declare a variable, before assigning this variable a value, the variable is named: undefined 2, msg = "Hello";/Not applicable VAR can declare a global variable, but this variable because it is global, so it is easy to cause other calls

Deep understanding of JavaScript functions _ Basics

Methods & Functions Difference 1.function is a more general concept, such as math, programming 2.method is an object-oriented concept that typically appears in pairs with classes or objects Relationship 1. The properties of an object can be any

JavaScript Basic Grammar _ Basics

1, operator An operator is a sequence of symbols that completes an operation, and it has seven classes: Assignment operators (=,+=,-=,*=,/=,%=,>=,|=,&=), arithmetic operators (+,-, *,/,++,--,%), Comparison operators (>,=,==,== =,!=,!==), logical

An analysis of undefined types in JavaScript and null types _ Basics

Undefinedindicates that the variable has been declared but has not been initialized. It should be noted that when the TypeOf operator is used to determine the data type, the values returned by the undeclared and uninitialized variables are undefined

A summary of the usage of flow control statements in JavaScript programs _ Basics

Conditional Judgment Statement 1.if statement if (condition) statement1 else statement2 The condition condition can be any expression, and the result of the evaluation of the expression is not necessarily a Boolean value. ECMAScript

About JavaScript | How to use the single vertical bar operator _ Basics

JS operator single vertical bar "|" The role In the JS integer operation, the equivalent of removing the decimal point, parseint. When a positive number is equivalent to Math.floor (), a negative number is equivalent to the Math.ceil () Note: 1.

Simple mastery of the use of Const declaration constants and variables in JavaScript basics

The third declaration class keyword introduced by ES6 is similar to let: Const. Take a look at the usage: Const C1 = 1; Const C2 = {}; CONST C3 = []; Object.getownpropertydescriptor (window, "C1") //object {value:1,

Several considerations for optimizing the performance of JavaScript scripts _ Basics

With the development of the network and the speed of the machine, more and more websites use the rich client technology. Now Ajax is one of the most popular ways. JavaScript is an interpreted language, so it can't reach the level of C/java and so on,

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