JavaScript String Search

String Search Methods

text.indexOf("World")     // 6
text.indexOf("xyz")       // -1

text.lastIndexOf("o")     // 15
text.lastIndexOf("xyz")   // -1

text.includes("World")    // true
text.includes("xyz")      // false

text.startsWith("Hello")  // true
text.startsWith("World")  // false

🔹 indexOf() and lastIndexOf()

Find the position of text within a string:

let text = "Hello World, Hello Universe";

// indexOf() - finds first occurrence
let first = text.indexOf("Hello");        // 0
let firstO = text.indexOf("o");           // 4
let notFound = text.indexOf("xyz");       // -1

// lastIndexOf() - finds last occurrence
let last = text.lastIndexOf("Hello");     // 13
let lastO = text.lastIndexOf("o");        // 15

// Search from specific position
let fromPos = text.indexOf("o", 5);       // 7 (starts search from index 5)

console.log("First 'Hello':", first);
console.log("First 'o':", firstO);
console.log("Not found:", notFound);
console.log("Last 'Hello':", last);
console.log("Last 'o':", lastO);
console.log("'o' from position 5:", fromPos);

🔹 includes() Method

Check if a string contains specific text:

let text = "JavaScript is awesome and powerful";

// Basic includes
let hasJS = text.includes("JavaScript");      // true
let hasJava = text.includes("Java");          // true
let hasPython = text.includes("Python");     // false

// Case sensitive
let hasjs = text.includes("javascript");     // false (case sensitive)

// Search from specific position
let hasAwesome = text.includes("awesome", 15); // true
let hasIs = text.includes("is", 15);          // false (not found after position 15)

console.log("Has 'JavaScript':", hasJS);
console.log("Has 'Java':", hasJava);
console.log("Has 'Python':", hasPython);
console.log("Has 'javascript' (lowercase):", hasjs);
console.log("Has 'awesome' from pos 15:", hasAwesome);
console.log("Has 'is' from pos 15:", hasIs);

🔹 startsWith() and endsWith()

Check if a string starts or ends with specific text:

let text = "JavaScript Programming Tutorial";

// startsWith() - check beginning
let startsWithJS = text.startsWith("JavaScript");    // true
let startsWithProg = text.startsWith("Programming"); // false
let startsWithProg2 = text.startsWith("Programming", 11); // true (from position 11)

// endsWith() - check ending
let endsWithTutorial = text.endsWith("Tutorial");    // true
let endsWithProg = text.endsWith("Programming");     // false
let endsWithJS = text.endsWith("JavaScript", 10);    // true (within first 10 chars)

console.log("Starts with 'JavaScript':", startsWithJS);
console.log("Starts with 'Programming':", startsWithProg);
console.log("Starts with 'Programming' from pos 11:", startsWithProg2);
console.log("Ends with 'Tutorial':", endsWithTutorial);
console.log("Ends with 'Programming':", endsWithProg);
console.log("Ends with 'JavaScript' in first 10 chars:", endsWithJS);

🔹 search() Method

Search using regular expressions:

let text = "JavaScript is Great! JavaScript rocks!";

// search() with string (similar to indexOf)
let searchString = text.search("JavaScript");     // 0

// search() with regular expression
let searchRegex = text.search(/great/i);          // 14 (case insensitive)
let searchNumber = text.search(/\d/);             // -1 (no numbers found)
let searchWord = text.search(/\bGreat\b/i);       // 14 (whole word, case insensitive)

// Complex patterns
let searchPattern = text.search(/Java\w+/);       // 0 (Java followed by word characters)

console.log("Search 'JavaScript':", searchString);
console.log("Search 'great' (case insensitive):", searchRegex);
console.log("Search for numbers:", searchNumber);
console.log("Search whole word 'Great':", searchWord);
console.log("Search 'Java' + word chars:", searchPattern);

🔹 match() Method

Extract matches using regular expressions:

let text = "Contact us at: [email protected] or [email protected]";

// match() with string
let matchString = text.match("email");
console.log("Match 'email':", matchString);

// match() with regular expression
let matchEmail = text.match(/\w+@\w+\.\w+/);      // First email
console.log("First email:", matchEmail[0]);

// match() with global flag
let matchAllEmails = text.match(/\w+@\w+\.\w+/g); // All emails
console.log("All emails:", matchAllEmails);

// match() with groups
let emailPattern = /(\w+)@(\w+)\.(\w+)/g;
let emailParts = text.match(emailPattern);
console.log("Email parts:", emailParts);