Sorting strings is to arrange strings in dictionary order or alphabetical order. When developing applications using JavaScript, it is common to sort arrays of strings. In this tutorial, we will learn to sort strings in JavaScript.
For example, if you get some data from an API and want to display that data in sorted order, string sorting is very useful here.
Here, we will learn to sort strings using built-in methods and various simple methods.
Use the sort() method to sort strings
In JavaScript, sort() is a built-in method that we can use on arrays. Generally speaking, in other programming languages, the sort() method sorts values by default. However, JavaScript converts numbers to strings and sorts them alphabetically.
Therefore, we can sort the string array using JavaScript's sort() method without using the comparator function.
grammar
Users can use the JavaScript sort() method to sort strings according to the following syntax.
Strings.sort();
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In the above syntax, we use string array as reference and sort() method.
Example 1
In this example, we define a string array and initialize it with some string values. After that, we take the array as a reference and execute the array's sort() method. The user can observe the output that all strings in the array are sorted alphabetically.
<html>
<body>
<h2>Using the <i>sort() method</i> to sort an array of strings in JavaScript.</h2>
<div id = "output"> </div>
<script>
let output = document.getElementById('output');
let strings = ["Hi", "JavaScript", "TypeScript", "C", "CPP", "Python", "Java", "HTML", "CSS"];
output.innerHTML += "The original string array is " + strings + "<br/>";
strings.sort();
output.innerHTML += "The sorted string array is " + strings + "<br/>";
</script>
</body>
</html>
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Use for loop to sort strings (bubble sort algorithm)
An easy way to sort a string is to use a for loop. We can use two nested for loops to compare each string to all other strings and sort them alphabetically. Also, we can say that it is a bubble sort algorithm.
grammar
Users can use the bubble sort algorithm to sort strings in alphabetical order according to the following syntax.
for (let a = 0; a < strings.length; a++) {
for (let b = a + 1; b < strings.length; b++) {
if (strings[a] > strings[b]) {
// swap strings at index a and index b
}
}
}
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In the above syntax, we use two nested for loops and iterate over the string array. Additionally, we compare two string values and based on this we swap the strings.
algorithm
Step 1 - Create an array of strings.
Step 2 - Use a for loop and iterate over the string array starting from the 0th index.
Step 3 - Within the for loop, use another for loop and start iterating the a 1st index, where a is the iteration pointer of the first for loop.
Step 4 - Now, compare the strings at ath and bth indices.
Step 5 - If the alphabetical order of the string at index ath is greater than the string at index b, swap the two strings.
Step 6 - Complete all iterations of both for loops to get all the strings in sorted order.
Example 2 (consider the case of string characters)
In the following example, we implement the bubble sort algorithm to sort an array of strings. The output below shows us that bubble sort algorithm sorts all strings where uppercase letters come before lowercase letters because uppercase letters have higher priority than lowercase letters in string comparison.
<html>
<body>
<h2>Using the <i> bubble sort algorithm </i> to sort an array of strings in JavaScript.</h2>
<div id = "output"> </div>
<script>
let output = document.getElementById('output');
let strings = ["car", "Bike", "truck", "cycle", "Tempo", "cart", "abcd", "string"];
output.innerHTML += "The original string array is " + strings + "<br/>";
for (let a = 0; a < strings.length; a++) {
for (let b = a + 1; b < strings.length; b++) {
if (strings[a] > strings[b]) {
let tempString = strings[a];
strings[a] = strings[b];
strings[b] = tempString;
}
}
}
output.innerHTML += "The sorted string array is " + strings + "<br/>";
</script>
</body>
</html>
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Example 3 (ignore the case of string characters)
In this example, we implemented the bubble sort algorithm to sort strings, but we compared lowercase strings. In the above example, we are sorting the string according to alphabetical order and sorting uppercase letters first. But here, we ignore case of string characters and compare strings.
<html>
<body>
<h2>Using the <i> bubble sort algorithm </i> to sort an array of strings in JavaScript.</h2>
<div id = "output"> </div>
<button onclick = "sortStrings()"> Sort Strings </button>
<script>
let output = document.getElementById('output');
let strings = ["ab", "Bc", "AB", "AC", "cd", "ds", "ds", "erere", "DS"];
output.innerHTML += "The original strings are " + strings + "<br/>";
function sortStrings() {
function swap(index1, index2) {
let tempString = strings[index1];
strings[index1] = strings[index2];
strings[index2] = tempString;
}
for (let a = 0; a < strings.length; a++) {
for (let b = a + 1; b < strings.length; b++) {
if (strings[a].toLowerCase() > strings[b].toLowerCase()) {
swap(a, b)
}
}
}
output.innerHTML += "The sorted strings are " + strings + "<br/>";
}
</script>
</body>
</html>
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We learned about sorting multiple strings in this tutorial. In the first method, we used the sort() method as it always sorts the string alphabetically. In the second method, we implemented the bubble sort algorithm to sort the strings, but we can optimize it to be more time efficient. Additionally, we can use other algorithms such as merge sort to improve the time and space efficiency of the sorting algorithm.
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