JavaScript String Search

In JavaScript, working with text often requires searching for specific words, phrases, or characters within a string. JavaScript provides several built-in string methods for searching, matching, and locating text.

This tutorial will teach you how to use key string search methods effectively, including indexOf(), lastIndexOf(), search(), includes(), match(), startsWith(), and endsWith().

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1. indexOf()

The indexOf() method returns the first position of a specified value in a string. If the value is not found, it returns -1.

javascriptCopyEditlet text = "JavaScript is awesome!";
let position = text.indexOf("is");
console.log(position); // 11

You can also pass a second argument to start searching from a specific index:

javascriptCopyEditconsole.log(text.indexOf("a", 2)); // 3

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2. lastIndexOf()

lastIndexOf() works like indexOf(), but it searches from the end of the string.

javascriptCopyEditlet phrase = "I love JavaScript and Java";
console.log(phrase.lastIndexOf("Java")); // 22

If not found, it returns -1.

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3. includes()

includes() checks if a string contains a specified substring. It returns true or false.

javascriptCopyEditlet msg = "Hello, world!";
console.log(msg.includes("world")); // true
console.log(msg.includes("World")); // false (case-sensitive)

You can also specify a start position:

javascriptCopyEditconsole.log(msg.includes("Hello", 5)); // false

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4. search()

The search() method searches for a match using a regular expression and returns the position of the first match. Unlike indexOf(), search() only accepts regular expressions.

javascriptCopyEditlet sentence = "The quick brown fox jumps over the lazy dog.";
let pos = sentence.search(/fox/);
console.log(pos); // 16

If no match is found, it returns -1.

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5. match()

The match() method searches a string for a match using a regular expression and returns the matched results.

Basic match:

javascriptCopyEditlet result = sentence.match(/fox/);
console.log(result[0]); // "fox"

Match all occurrences (with global flag g):

javascriptCopyEditlet text = "cat bat rat cat";
let matches = text.match(/cat/g);
console.log(matches); // ["cat", "cat"]

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6. startsWith()

This method checks if a string starts with the given substring.

javascriptCopyEditlet greeting = "Hello, world!";
console.log(greeting.startsWith("Hello")); // true
console.log(greeting.startsWith("world")); // false

You can also pass a position to start checking from:

javascriptCopyEditconsole.log(greeting.startsWith("world", 7)); // true

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7. endsWith()

This method checks if a string ends with the given substring.

javascriptCopyEditlet filename = "report.pdf";
console.log(filename.endsWith(".pdf")); // true

You can also check against a portion of the string:

javascriptCopyEditconsole.log(filename.endsWith("report", 6)); // true

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8. Comparing Search Methods

Method	Returns	Use Case
indexOf()	Index or -1	Find position of a substring
lastIndexOf()	Last index or -1	Find last occurrence
includes()	true or false	Check if text exists
search()	Index or -1	Search using regular expressions
match()	Array or null	Extract matched values
startsWith()	true or false	Check string start
endsWith()	true or false	Check string end

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9. Case Sensitivity

All string search methods in JavaScript are case-sensitive by default.

javascriptCopyEditlet word = "JavaScript";
console.log(word.includes("java")); // false

To do case-insensitive searching, use regular expressions with the i flag:

javascriptCopyEditconsole.log(word.search(/java/i)); // 0

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10. Real-World Example: Simple Search Filter

javascriptCopyEditlet products = ["Laptop", "Phone", "Tablet", "Monitor"];
let keyword = "ph";

let filtered = products.filter(item => item.toLowerCase().includes(keyword.toLowerCase()));
console.log(filtered); // ["Phone"]

This technique is useful in search bars and filter systems.

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Conclusion

JavaScript offers several powerful string search methods. Here’s a quick recap:

• Use indexOf() and lastIndexOf() for positions.
• Use includes() to check if a string exists.
• Use search() and match() for regular expressions.
• Use startsWith() and endsWith() to check string boundaries.