April 27, 2022

How to Check if String Starts with HTTP or HTTPS in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to check if string starts with HTTP or HTTPS in javascript. A URL is just a unique address of a resource on the web. URL stands for Uniform Resource Locator. For a newbie developer, it can be a bit tricky to find if a string starts with HTTP or HTTPS.

HTTP stands for hypertext transfer protocol. It is a standard application-level protocol used for exchanging files over the internet. HTTPS stands for hypertext transfer protocol secure. It is an extension of HTTP and is widely used to transfer encrypted HTTP data over the internet.

There are numerous ways to check if a string starts with HTTP or HTTPS. We are going to use one of the easiest solutions which involve the usage of the startsWith() method and ternary (?) operator.

The startsWith() method checks whether a given string starts with a specified string or not. The ternary operator is also known as the conditional operator which acts similar to the if-else statement.

In the following example, we have one global variable which holds an URL string and upon click of a button, we will check if the string starts with HTTP or HTTPS and display the result on the screen. Please have a look over the code example and the steps given below.

HTML & CSS

We have 3 elements in the HTML file (div, button, and h1). The div element is just a wrapper for the rest of the elements.
The innerText for the button element is “Check” and for the h1 element, it is “Result”.
We have done some basic styling using CSS and added the link to our style.css stylesheet inside the head element.
We have also included our javascript file script.js with a script tag at the bottom.

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">
  <title>Document</title>
</head>

<body>

  <div class="container">    
    <button>Check</button>
    <h1>Result</h1>
  </div>

  <script src="script.js"></script>
</body>

</html>

.container {        
    text-align: center;
}

button {
  margin-top: 10px;
  padding: 10px 20px;
}

Javascript

We have selected the button element and h1 element using the document.querySelector() method and stored them in btnCheck and output variables respectively.
We have a global variable myVar which holds a https URL as its value.
We have attached a click event listener to the button element.
In the event handler function, we are calling getProtocol() method and passing it myVar as a parameter. This method will verify whether myVar starts with http or https.
In the getProtocol() method, we are using startsWith() method and ternary (?) operator as well as switch statement for verification. Depending upon the result of the check, this method will return "http", “https”, or “Not http or https”.
We are assigning the returned value to the result variable.
We are displaying the result in the h1 element using the innerText property.

let btnCheck = document.querySelector("button");
let output = document.querySelector("h1");

let myVar = "https://www.mytestsite.com/";

btnCheck.addEventListener("click", () => {
  let result = getProtocol(myVar)
  output.innerText = result;
});

function getProtocol(url) {
  let protocol = url.startsWith("http://") ? 1 : 0;
  if (protocol == 0) protocol = url.startsWith("https://") ? 2 : 0;

  switch (protocol) {
    case 1:
      return "http";
    case 2:
      return "https";
    case 0:
      return "Not http or https";
  }
}

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