Turn on the browser javascript function, and enable javascript in the browser settings

This article will talk about the benefits of turning on JavaScript in the browser and how to set up the browser to support JavaScript. I hope it will be helpful to you. Don’t forget to bookmark this site.

(1) JavaScript about browsers

JavaScript about browsers

JavaScript runs in browsers. Different browsers have different support for JavaScript. When writing JavaScript, you must consider the differences in browsers and try your best to make it run in different browsers.

1. Objects in the browser

1.window

Window: Represents the window opened by the browser and serves as the global scope for python for statement usage. There is no need to specify it when using the properties and methods of Windows objects (generally follow the custom: for example, window.alert() is usually alert()).

Attribute name	Function
name	Specify the name of the window
parent	The parent window of the current window (frame), use it to return the methods and properties of the object
opener	Returns the window object that created the current window, using its methods and properties to return the object
top	Represents the main window, which is the top-level window and the parent window of all other windows. The methods and properties of the current window can be accessed through this object
self	Returns an object of the current window through which the methods and properties of the current window can be accessed
defaultstatus	Returns or sets the default content that will be displayed in the browser status bar
status	Returns or sets the specified content that will be displayed in the browser status bar

Method name	Function
alert()	Displays an alert dialog box containing a message and an OK button
confirm()	Show a confirmation dialog
prompt()	Displays a prompt dialog box prompting the user to enter data
open()	Open an existing window or create a new window and load a document in it
close()	Close an open window
navigate()	Display the specified web page in the current window
setTimeout()	Set a timer to call a function after a specified interval
clearTimeout()	Reset the specified timer
focus()	Gives a Window object the current focus
blur()	Causes a Window object to lose its current focus

Event	Description
onload	Occurs when an HTML file is loaded into the browser
onunload	Occurs when an HTML file is deleted from the browser
onfocus	Occurs when a window gains focus
onblur	Occurs when a window loses focus
onhelp	Occurs when the user presses the F1 key
onresize	Occurs when the user resizes the window
onscroll	Occurs when the user scrolls the window
onerror	Occurs when there is an error loading the HTML file

Some operations for Window:

alert('window inner size: ' + window.innerWidth + ' x ' + window.innerHeight);//Get the window size
window.confirm('Information displayed in the dialog box!');
mu = window.open("http://www.baidu.com","","width=200,height=100");//Open a web page, you can also have only the url in it, and the other defaults
mu.moveTo(1600,584);//Where to move the window
mu.moveBy(-111,-111);//How much is the displacement based on xy
mu.resizeTo(800,400);//Change the window size to w800, h400
var a =prompt("Please enter your name", "Contents of the text box when empty");//Input prompt box and return the input content
alert(a);

Some timing operations:

There are four timing operation functions: window.setInterval, window.clearInterval, window.setTimeout, and window.clearTimeout. These four functions are all methods of the window object, which shows that timing operations in the browser are completed by the browser window. (unit ms)

① window.setInterval sets the timer and executes the specified code at regular intervals window.setInterval(code,time);

② window.clearInterval clears the timer set by the setInterval function window. clearInterval(time);

③ window.setTimeout sets the timer and executes the specified code at regular intervals. window.setTimeout(code, time); the code is only executed once.

④ window.clearTimeout clears the timer set by the setTiimeout function window.clearTimeout(time);

A piece of code for dynamically displaying time: Set a timer, the timer executes the clock() function every 1000ms, and assigns the value to the text box in the function.

<html>
  <language=java>
    var int=self.setInterval("clock()",1000);
    function clock(){
      var t=new Date();
      document.getElementById("clock").value=t;
    };
  </>
<body>
<input type="text" id="clock" size="35" />
<button οnclick="int=window.clearInterval(int)">Stop timer</button>
</body>
</html>

A code that displays the time on the page:

<html>
  <language=java>
    var int=self.setInterval("clock()",1000);
    function clock(){
      var t=new Date();
      var hehe = document.getElementById("ck");
      hehe.innerText=t;
    };
  </>
<body>
<p id="ck">...</p>
<button οnclick="int=window.clearInterval(int)">stop</button>
</body>
</html>

2.navigator

The navigation object contains information about the browser itself; this information can be modified, so use this to determine what is incorrect.

The navigator object represents browser information. The most commonly used attributes include:

navigator.appName: browser name;

navigator.appVersion: browser version;

navigator.language: The language set by the browser;

navigator.platform: operating system type;

navigator.userAgent: User-Agent string set by the browser

alert('appName = ' + navigator.appName + '\
' +
      'appVersion = ' + navigator.appVersion + '\
' +
      'language = ' + navigator.language + '\
' +
      'platform = ' + navigator.platform + '\
' +
      'userAgent = ' + navigator.userAgent);

3.scree

The screen object contains information about the client screen and rendering capabilities;

screen.width: screen width, in pixels;

screen.height: screen height, in pixels;

screen.colorDepth: Returns the number of color digits, such as 8, 16, 24.

alert('Screen size = ' + screen.width + ' x ' + screen.height)

4.location

The location object contains the browser’s current URL information;

var b = location.href;//Get the complete URL
alert(b);
location.protocol; // Protocol 'http'
location.host; //Address 'www.xxx.com'
location.port; //Port number '8080'
location.pathname; // path '/path/index.html'
location.search;
location.hash;

The location method reloads the page, reloads the current page and loads a new page.

if (confirm('Reload current page' + location.href + '?')) {
    location.reload();
} else {
    location.assign('https://www.baidu.com/index.php?tn=monline_3_dg'); // Set a new URL address
}

5.document

The document object represents the document object of the page loaded in the browser;

document.getElementById('unid');//Get this object
document.getElementsByTagName('input');

The document object also has a cookie attribute, which can obtain the cookie of the current page. (The server can distinguish users from this)

document.cookie;

JavaScript can read the cookie of the page. When setting the cookie on the server side, you should always insist on using httpOnly; this behavior is implemented by the browser. After setting, JavaScript cannot read the cookie. All mainstream browsers support httpOnly. options.

6.history

The forward and back methods are like the browser’s forward and back functions.

history.forward();//Forward
history.back();//Back