How to make a function to go after an element [duplicate]

Question

In JavaScript, you will often see functions which say document.getElementById("element").someFunction(); or $("element").someFunction(); instead of someFunction($("element"));. Where someFunction(element) looks a little like the following code.

someFunction(element) {
    //element.doSomething();
}

My question is how do you make a function which manipulates the element it is attached to instead of manipulating an element passed through as an argument?

Answer 1

You can achieve it using prototype

// `getElementById` returns a `Element` object so extend it's prototype
Element.prototype.someFunction = function(){
   // this.somethig
}

document.getElementById("element").someFunction();

Element.prototype.someFunction = function() {
  console.log(this.value)
}

document.getElementById("element").someFunction();

<input value="abc" id="element" />

---

Note : It's really bad practice to extend prototype of native object.

Answer 2

You are looking for prototypes

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/prototype

element.prototype.someFunction = function(){
  this.doSomething(); // this refers to element
}