The Web Storage API is a simple syntax for storing and retrieving data in the browser. It is very easy to use:
localStorage.setItem("name", "John Doe");
localStorage.getItem("name");
The Web Storage API is supported in all browsers:
| Chrome | IE/Edge | Firefox | Safari | Opera |
| Yes | Yes | Yes | Yes | Yes |
The Web History API provides easy methods to access the windows.history object.
The window.history object contains the URLs (Web Sites) visited by the user.
The Web History API is supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera |
|---|---|---|---|---|
| Yes | Yes | Yes | Yes | Yes |
The back() method loads the previous URL in the windows.history list.
It is the same as clicking the “back arrow” in your browser. Continue reading Javascript Web History API
| Property | Description |
|---|---|
| checkValidity() | Returns true if an input element contains valid data. |
| setCustomValidity() | Sets the validationMessage property of an input element. |
If an input field contains invalid data, display a message:
<input id="id1" type="number" min="100" max="300" required>
<button onclick="myFunction()">OK</button>
<p id="demo"></p>
<script>
function myFunction() {
const inpObj = document.getElementById("id1");
if (!inpObj.checkValidity()) {
document.getElementById("demo").innerHTML = inpObj.validationMessage;
}
}
</script>
A Web API is a developer’s dream.
API stands for Application Programming Interface.
A Web API is an application programming interface for the Web.
A Browser API can extend the functionality of a web browser.
A Server API can extend the functionality of a web server. Continue reading Javascript Web APIs – Introduction
Cookies let you store user information in web pages.
Cookies are data, stored in small text files, on your computer.
When a web server has sent a web page to a browser, the connection is shut down, and the server forgets everything about the user.
Cookies were invented to solve the problem “how to remember information about the user”:
Cookies are saved in name-value pairs like:
username = John Doe
When a browser requests a web page from a server, cookies belonging to the page are added to the request. This way the server gets the necessary data to “remember” information about users. Continue reading JavaScript Cookies
The window object allows execution of code at specified time intervals.
These time intervals are called timing events.
The two key methods to use with JavaScript are:
setTimeout(function, milliseconds)
setInterval(function, milliseconds)The setTimeout() and setInterval() are both methods of the HTML DOM Window object.
JavaScript has three kind of popup boxes: Alert box, Confirm box, and Prompt box.
An alert box is often used if you want to make sure information comes through to the user.
When an alert box pops up, the user will have to click “OK” to proceed. Continue reading JavaScript Popup Boxes
The window.navigator object contains information about the visitor’s browser.
The window.navigator object can be written without the window prefix.
Some examples:
navigator.cookieEnablednavigator.appCodeNamenavigator.platformThe window.history object contains the browsers history.
The window.history object can be written without the window prefix.
To protect the privacy of the users, there are limitations to how JavaScript can access this object.
Some methods:
history.back() – same as clicking back in the browserhistory.forward() – same as clicking forward in the browserThe window.location object can be used to get the current page address (URL) and to redirect the browser to a new page.
The window.location object can be written without the window prefix.
Some examples:
window.location.href returns the href (URL) of the current pagewindow.location.hostname returns the domain name of the web hostwindow.location.pathname returns the path and filename of the current pagewindow.location.protocol returns the web protocol used (http: or https:)window.location.assign() loads a new document