Creating a jquery plugin

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Jquery has been used quite largely in many web projects because it gives you all javascript functions and commands wrapped in a nice API interface. For example: "jquery selectors", used very heavily.

Also, there were a lot of plugins which were build on top of jquery. for example: bootstrap's modal, tooltip etc.

Example usage of bootstrap modal:

$("#target").modal("show")

Whenver we use $ instead of document.querySelector() it returns a jquery object which has some methods available like .css(), .click() etc.

Jquery object gets these methods from $.fn object

So, let's say we want to write our own method and add it in $.fn definition so that every jquery object can also use that method.

Let's take a use case of Dropcap/s. We want to apply a function on a jquery object which will basically make the first letter bigger in size relative to the sentence or paragraph. (Something like we see in newsletters 🤔)

Let's name this function dropCap and the definition will look somthing like this:

$.fn.dropCap = function () {
  // your definition goes here
}

We can use this function on any jquery object now:

$(".some-element").dropCap()

and it will execute whatever functionality we write in our dropCap function.

Protecting the $ Alias and Adding Scope

Detail explanation

Since the $ variable is very popular among JavaScript libraries, we need to scope it and map it to jQuery variable by using a Immediately Invoked Function Expression

;(function ($) {
  $.fn.dropCap = function () {
    // your definition goes here
  }
})(jQuery)

⏲ Now, we can write some css for our dropCap class

.dropCap {
  font-size: 2.4em;
  font-weight: 700;
  margin-right: 5px;
}

This will give the dropcap effect when we apply this class to first letter.

Let's finallly add the code for our plugin

;(function ($) {
  $.fn.dropCap = function () {
    val = this.text()
    first_letter = val.substring(0, 1)
    dropCapLetter = `<span class='dropCap'>${first_letter}</span>`
    this.html(dropCapLetter + val.substring(1))
  }
})(jQuery)

Above function reads the passed jquery object and updates the first letter of the paragraph as dropCap letter.

Codepen example

Thanks for reading, I hope it was helpful in some way 😃✨

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References

Advance plugin concepts