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1, the concept: JavaScript abbreviation JS, is running in the browser side of a script language, code does not need to compile, can run directly, and read into a line, run a line, more for: browser-side verification, Ajax, rich clients, etc.
2, write the location:
Inside the tag: write the JS event code inside the tag
Inside the page: in the <script> </script> tag internal write JS code
In the <body></body>
In the
External. JS file:<script type= "Text/javascript" src= "script.js" ></script>
3. JavaScript Comments:
Single-line Comment://
Multiline Comment:/* */
4. Mouse events:
OnClick: Mouse Click event to execute script when mouse click
OnDblClick: Mouse Double-click event, double-click Element Execution Script
onMouseOver: Mouse over event, execute script when mouse moves on element
onMouseOut: Executes the script when the mouse moves out of the element
OnMouseUp: Execute script when mouse button is released
OnMouseDown: Executes the script when the mouse button is pressed
OnMouseMove: Execute script when mouse pointer moves
code example:
1 <!DOCTYPE HTML>2 <HTML>3 <Head>4 <MetaCharSet= "UTF-8">5 <title>Insert Title here</title>6 <Scripttype= "Text/javascript"src= "Script.js"></Script>//External JS7 <Scripttype= "Text/javascript">//8 window.onload=function() {//= called when page load is complete9 varbtn=document.getElementById ("Btn3");Ten Btn.onclick=function(){ One Alert ("Point 3"); A } - } - </Script> the </Head> - <Body> - <ButtonID= "BTN1"onclick= "alert (' point 1 ')">Point 1</Button>//tags inside js - <ButtonID= "BTN2">Point 2</Button> + <ButtonID= "Btn3">Point 3</Button> - <ButtonID= "Btn4">Point 4</Button> + <Scripttype= "Text/javascript">//<body></body> inside JS A varbtn=document.getElementById ("btn2"); at Btn.onmouseover=function(){ - Alert ("page: Point 2! "); - } - </Script> - </Body> - </HTML>
Code in Script.js:
1 window.onload=function() {2 var btn=document.getelementbyid (" Btn4 "); 3 btn.onclick=function() {4 alert ("External: Why do you order me! "); 5 }; 6 };Where the button "point 3" of the JS code will not be executed, because Window.onload will only be called once, first called the external JS in the Window.onload
5. Variables:
Disclaimer: JS is a weakly typed language, you do not need to specify the type of variable when declaring a variable, you only need to use the var keyword
Assignment: JS is a dynamic type of language, you can assign any type of value to a variable, you can change the type of the variable in the process of use
6. Functions
In JS, the function is also an object, you can assign a function reference to a variable
JS in the function does not check the type and number of parameters, so there is no overload this thing
Functions: including definition of functions, invocation of functions
Declaration of function: function declaration by using Functions keyword
Anonymous functions:
var a=function () {//anonymous function
Alert ("function a");
}
Named functions:
function sum (A, b) {
var sum=a+b;
return sum;
}
Invocation of function: reference to function + ();
A ();
sum (2,3);
Function of return: 1, execution of termination function; 2. Return the result of the function to the caller
7. Objects
There are two ways of creating objects in JS:
1, var obj=new Object ();
2, Var obj={};
To add properties and methods dynamically to an object:
Getting Started with JavaScript
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