JavaScript knowledge points

Last Update:2016-07-13 Source: Internet

Author: User

Tags diff

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<!doctype html>

<title>index </title>

<body>

</body>

*******************************************************************************

Date object:

var mydate=new Date ();

var datestring=mydate.tolocaledatestring () + "" +mydate.tolocaletimestring ();

var Dateloc=document.getelementbyid ("Datefield");

Dateloc.innerhtml= "Hello-page Rendered on" +datestring;

*******************************************************************************

Countdown to one day in the future:

var today=new Date ();

var then=new Date ();

Then.setfullyear (2012,0,1);

var diff=then.gettime ()-today.gettime (); GetTime () is given in milliseconds.

Diff=math.floor (diff/(1000*60*60*24));

var Dateloc=document.getelementbyid ("datefiled");

Dateloc.innerhtml= "There is" +diff+ "days until 1/1/2012";

*******************************************************************************

Calculate Render Time:

var started=new Date ();

var now=started.gettime ();

var bottom=new Date ();

var diff= (Bottom.gettime ()-now)/1000;

var finaltime=diff.toprecision (5);

var Dateloc=document.getelementbyid ("datefiled");

Dateloc.innerhtml= "page rendered in" +finaltime+ "seconds.";

Delay:

for (Var i=0;i<100000;i++) {

Delay

}

*******************************************************************************

Regular Expressions:

var mystring= "http://www.braingia.org";

var myregex=/http:\/\/\w+\. (.*)/;

var results=myregex.exec (myString);

Alert (results[1]);

Match Method:

var emailaddr= "[email protected]";

var myregex=/\.com/;

var checkmatch=emailaddr.match (Myregex);

Alert (checkmatch[0]);

Determines whether a given email address contains a string . com:

var emailaddr= "[email protected]";

var myregex=/\.com/;

var checkmatch=emailaddr.match (Myregex);

if (checkmatch!==null) {

Alert (checkmatch[0]);

}

Search Method:( Returns the index value (location) of the first match)

var emailaddr= "[email protected]";

var myregex=/\.com/;

var searchresult=emailaddr.search (Myregex);

Alert (checkmatch[0]);

Replace method:

var emailaddr= "[email protected]";

var myregex=/\.com$/;

var replacewith= ". Net";

var result=emailaddr.match (Myregex);

alert (result);

*******************************************************************************

Using the detele operator:

var star={};

star["Polaris"]=new object;

star["Mizar"]=new object;

star["Aldebaran"]=new object;

star["Rigel"]=new object;

star["Polaris"].constellation= "Ursa Minor";

star["Mizar"].constellation= "Ursa Minor";

star["Aldebaran"].constellation= "Ursa Minor";

star["Rigel"].constellation= "Ursa Minor";

Detele (star["Polaris"].constellation);

For (Starname in Star) {

var para=document.createelement (' P ');

Para.id=starname;

Para.appendchild (document.createTextNode (starname+ ":" +star[starname].constellation));

document.getElementsByTagName ("Body") [0].appendchild (para);

}

*******************************************************************************

For in Loop:

for (Var myprop in MyObject) {

Alert (myprop+ "=" +myobject[myprop]);

}

Var star=new object;

Star.name= "";

Star.type= "";

Star.constellation= "";

for (Var starprop in Star) {

Alert (starprop+ "=" +star[starprop]);

}

*******************************************************************************

Form validation:

<!doctype html>

<title> Sentiment analysis results </title>

<body>

<p>username:<input id= "Nametext" name= "Username" type= "text"/></p>

</form>

</body>

function Alertname () {

var Name=document.forms[0].nametext.value;

if (name== "Steve") {

Alert ("Hello Steve. Welcome to Machine ");

}

else if (name== "Nancy") {

Alert ("Hello Tim.");

}

else{

Alert ("Hello" +name);

}

return true;

}

*******************************************************************************

W Some properties of the Indow object:

Close: set to True when the window is closed ;

Defaultstatus: Used to set the default text that appears in the browser status bar;

Name: The window that is set when the window is opened for the first time;

Opener: Refers to the window that created the window;

Parent: often used in conjunction with frames, a window that creates a particular window, or the upper-level window of that frame;

Status: Often used to set the text in the status bar when a visitor hovers over an element such as a link;

Top: Parent window of the highest or topmost level;

*******************************************************************************

Some methods of the Window object:

AddEventListener (): cross-browser (except Internet Explorer) event handler method.

Attachevent (): cross-browser Internet Explorer event handler method.

Blur (): Move the keyboard input focus away from the browser window.

Focus (): moves the keyboard input focus to the browser window.

Close (): closes the browser window.

DetachEvent (): cross-browser Internet Explorer event handler removal method.

RemoveEventListener (): cross-browser (except Internet Explorer) event handler removal method.

Open (): opens a window.

Print (): causes the printer function to invoke the browser, which behaves as if someone clicked the browser's print button.

*******************************************************************************

W Indow How to move and resize a Window object:

Moveby (): used to move the window to a relative position

MoveTo (): used to move the window to a specific location

Resizeby (): used to change the window size by a relative amount

Resizeto (): used to change the window size to a specific size

*******************************************************************************

W Timer-related methods in the Indow object:

Clearinterval ():

Cleartimeout ():

SetInterval ():

SetTimeout ():

*******************************************************************************

Get information about the screen:

Availheight/availwidth ( usable height )/colordepth/height/width (total height)

E.g:alert (Screen.availheight);

*******************************************************************************

Get element:

getElementById () and getElementsByTagName ()

HTML Collection:

Document.anchors

Document.forms

Document.images

Document.links

*******************************************************************************

Window Size:

var w=window.innerwidth

|| Document.documentElement.clientWidth

|| Document.body.clientWidth;

var h=window.innerheight

|| Document.documentElement.clientHeight

|| Document.body.clientHeight;

JavaScript knowledge points

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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