Summary of common javascript functions_javascript skills

1. The meaning of path symbols
src="/js/jquery.js", "../" The slash means an absolute path, which represents the root directory of the website.
Others such as "./", "../", "jquery.js", "js/jquery.js", etc. represent paths relative to the current web page and are relative paths.
2. Get the root directory of the website

Copy the code The code is as follows:

function GetRootPath() {
var strFullPath = window.document.location.href;
var strPath = window.document.location.pathname;
var pos = strFullPath.indexOf(strPath);
var prePath = strFullPath.substring(0, pos);
var postPath = strPath.substring(0, strPath.substr(1).indexOf('/') 1);
return (prePath postPath ;
The code is as follows:

//The url of the website is: http://www.A.COM?a=12 String.prototype.getQuery = function (name) { var reg = new RegExp("(^|&)" name "=([^&]*)(&|$)");
var r = this.substr(this.indexOf("?" ) 1).match(reg);

if (r != null) return unescape(r[2]); return null; } var strHref = window.location.href; alert(strHref.getQuery("a"));

4. Functions in js

4.1 Math.round rounding




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The code is as follows:

document.write(Math.round(0.60) "
") 1 document.write(Math.round(0.50) "
") 1
document.write(Math.round(0.49) "
") 0
document. write(Math.round(-4.40) "
") -4

document.write(Math.round(-4.60)) -5 4.2 Math.random () returns a random number between 0 and 1.

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The code is as follows:


document.write(Math.random())

document.write(Math.floor(Math.random()*11)) The floor() method and random() of the Math object to return a random number between 0 and 10

4.3 isNaN() Whether it is a non-number, if it is a non-number true, otherwise false 4.4 Number() Convert the value of the object to a number 4.5 parseFloat() parseInt() If the first character of the string cannot be Converting to a number will return NaN 4.6 String() function converts the value of the object into a string 5. Array

5.1 Merge arrays into arrays concat merges arrays to generate a new array , the original array remains unchanged

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The code is as follows:

var arr = new Array(3 )//Define array
arr[0] = "George" arr[1] = "John"
arr[2] = "Thomas"

var arr1 = new Array(3) arr1[0] = "James" arr1[1] = "Adrew" arr1[2] = "Martin" var arr2=arr.concat(arr1))

5.2 Arrays are combined into string join. The default is "," connection, which can be specified, such as join(".")

6. The most commonly used regular expression is test(), if found, it is true, otherwise it is false





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The code is as follows:

var patt1=new RegExp("e"); document .write(patt1.test("The best things in life are free"));

7. Events 7.1 onload and onUnload page loading, called when unloading 7.2 onFocus, onBlur and onChange events are usually used together to validate the form 7.3 onSubmit is used to verify all form fields before submitting the form

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The code is as follows:

/*
The following is an example of using the onSubmit event. When the user clicks the confirm button in the form, the checkForm() function is called. If the field value is invalid, the submission will be cancelled. The return value of the checkForm() function is true or false. If the return value is true, submit the form, otherwise cancel the submission. */

8. cookie
8.1 Create

Copy code The code is as follows:

function setCookie(c_name,value,expiredays)
{
var exdate=new Date()
exdate.setDate(exdate.getDate() expiredays)
document.cookie=c_name "=" escape(value)
((expiredays==null) ? "" : ";expires=" exdate.toGMTString())
}

8.2 Read

Copy code The code is as follows:

function getCookie(c_name)
{
if ( document.cookie.length>0)
{
c_start=document.cookie.indexOf(c_name "=")
if (c_start!=-1)
{
c_start=c_start c_name .length 1
c_end=document.cookie.indexOf(";",c_start)
if (c_end==-1) c_end=document.cookie.length
return unescape(document.cookie.substring( c_start,c_end))
}
}
return ""
}

9. Timing
setTimeout() Start timing
var t=setTimeout("javascript statement", milliseconds) clearTimeout(t) //Stop timing
10. Open the website
10.1 Open the website in another window window.open()

Copy code The code is as follows:

function openW(v){
var str = 'width=200,height=200,left=200,top=200,status=no,scrollbars=no,'
str = 'menubar=no,toolbar=no,resizable=no,location=no'
window.open(v,'',str);
}

10.2 Open the website in the same window
window.location.href ='http://www.sohu .com' ;
11. Object
11.1 Object definition, destruction

Copy code The code is as follows:

var oObject = new Object;
// do something with the object here
oObject = null;

11.2 Defining Classes

Copy code The code is as follows:

function Cat(name,color){
　this.name = name;
This.color = color;
this.type = "Feline";


11.3 Use JSON to construct an object

Copy code The code is as follows:

var People = {

Create: function (name, age) {
this.name = name;
this.age = age;
},
SayHello: function ( ) {
alert("Hello,My name is " this.name ".I am " this.age);
}
};


11.4 Use prototype to construct An object

Copy code The code is as follows:

var Person = function (name, age) {

this.name = name;
this.age = age;
};
Person.prototype.Introduce = function () {
alert("My name is " this.name " .I'm " this.age);
}