April 5, 2022

How to Find Length of String in Javascript Without Using Length Method

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to find length of string in javascript without using length method. The length of a string represents the total number of characters in that string.

There are numerous ways to find the length of a string. For the sake of simplicity, we always use length property. But today, we are going to use reduce() method. This method executes a reducer function on each element of an array.

In the following example, we have one global variable that holds a string. Upon click of a button, we will find the length of the string and display it 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 “Get” 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>Get</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 btnGet and output variables respectively.
We have a global variable myString which holds a string as its value.
We have attached a click event listener to the button element.
In the event handler function, we are calling getStringLength() method and passing myString as a parameter. This method will return length of the string.
In the getStringLength() method, we are using Array.from() method to convert string into an array of characters.
We are also using reduce() method and providing 0 as the second parameter to act as our default accumulated value to start with. If you do not provide it, then reduce method will pick the first element from the array. In case, your array is empty and there is no default accumulated value, then you will get an error. That’s why it is important to provide some default accumulated value to start with.
We are assigning the returned value to the length variable and returning it.
We are assigning the returned value from getStringLength()to the result variable.
We are displaying the result in the h1 element using the innerText property.

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

let myString = "Hello world";

btnGet.addEventListener("click", () => {  
  let result = getStringLength(myString);
  output.innerText = result;
});

function getStringLength(str){
  let length = Array.from(str).reduce(function(count){return count+1}, 0);
  return length
}

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