April 10, 2022

How to Check if a String Contains All Alphabets in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to check if a string contains all alphabets in javascript. Pangram refers to a word or a sentence that contains every letter of the alphabet at least once.

There are numerous ways to check if a string contains all the alphabets. But for the sake of simplicity, we will use the toLowerCase() method, replace() method, and Set() object to accomplish our goal.

The toLowerCase() method converts all letters in a string to lowercase. The replace() method searches the string for a particular value or a regex pattern and it returns a new string with the replaced values.

The Set() object in javascript allows you to store type agnostic values, which means you can store any value of any data type. All the values in the collection will be unique.

In the following example, we have one global variable that holds a string. Upon click of a button, we will check if the string contains all the alphabets 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 attached a click event listener to the button element.
We have a global variable myString which holds a string as its value.
In the event handler function, we are calling the isPangram() method and passing myString as a parameter. This method will check if the string contains all the alphabets and return a Boolean value.
In the isPangram() method, we are using the toLowerCase() method to convert the string into a lowercase string. Further, we are using replace() method to replace all non-letters with an empty string. We are storing the returned string in the value variable.
We are using Set() constructor and value variable to create a Set() object. As you know, there are around in total of 26 alphabets. We are checking whether the size of the Set() object is equal to 26 or not. This check will give as a Boolean and we will simply return it.
Depending upon the result of the check, we will assign “Yes” or “No” 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 myString = "The quick brown fox jumps over the lazy dog";

btnCheck.addEventListener("click", () => {
  let result = isPangram(myString) ? "Yes" : "No";
  output.innerText = result;
});

function isPangram(str) {
  let value = str.toLowerCase().replace(/[^a-z]/g, "");  
  return new Set(value).size === 26;
}

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