Here's the way to do it without using any external libraries:
// Define a class like this
function Person(name, gender){
// Add object properties like this
this.name = name;
this.gender = gender;
}
// Add methods like this. All Person objects will be able to invoke this
Person.prototype.speak = function(){
alert("Howdy, my name is" + this.name);
};
// Instantiate new objects with 'new'
var person = new Person("Bob", "M");
// Invoke methods like this
person.speak(); // alerts "Howdy, my name is Bob"
Now the real answer is a whole lot more complex than that. For instance, there is no such thing as classes in JavaScript. JavaScript uses a prototype
-based inheritance scheme.
In addition, there are numerous popular JavaScript libraries that have their own style of approximating class-like functionality in JavaScript. You'll want to check out at least Prototype and jQuery.
Deciding which of these is the "best" is a great way to start a holy war on Stack Overflow. If you're embarking on a larger JavaScript-heavy project, it's definitely worth learning a popular library and doing it their way. I'm a Prototype guy, but Stack Overflow seems to lean towards jQuery.
As far as there being only "one way to do it", without any dependencies on external libraries, the way I wrote is pretty much it.
Most of the jQuery Ajax methods return an XMLHttpRequest (or the equivalent) object, so you can just use abort()
.
See the documentation:
- abort Method (MSDN). Cancels the current HTTP request.
- abort() (MDN). If the request has been sent already, this method will abort the request.
var xhr = $.ajax({
type: "POST",
url: "some.php",
data: "name=John&location=Boston",
success: function(msg){
alert( "Data Saved: " + msg );
}
});
//kill the request
xhr.abort()
UPDATE:
As of jQuery 1.5 the returned object is a wrapper for the native XMLHttpRequest object called jqXHR. This object appears to expose all of the native properties and methods so the above example still works. See The jqXHR Object (jQuery API documentation).
UPDATE 2:
As of jQuery 3, the ajax method now returns a promise with extra methods (like abort), so the above code still works, though the object being returned is not an xhr
any more. See the 3.0 blog here.
UPDATE 3: xhr.abort()
still works on jQuery 3.x. Don't assume the update 2 is correct. More info on jQuery Github repository.
Best Answer
I have written an extension to jsPDF a while back that allows text aligning (and by default aligns top-left, instead of the random stuff jsPDF' .text function does).
The code is written in TypeScript (to add some type annotations), which should give you a pretty clear idea what parameters there are.
Update: These snippets have been corrected to work in the latest version as of 2019/07/17, thanks to Kaddath (see their comment/this post's edit history for details).
Plain javascript:
Using it is as simple as:
Prints a text of which the middle right is at (xPosition, yPosition).