Anagram Check

Program to check if two strings are anagrams

IntermediateTopic: String Programs
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JavaScript Anagram Check Program

This program helps you to learn the fundamental structure and syntax of JavaScript programming.

Try This Code
// Anagram: Same characters, different order
// Examples: "listen" and "silent", "evil" and "vile"

// Method 1: Sort and compare
function isAnagram1(str1, str2) {
    // Normalize: lowercase, remove spaces
    str1 = str1.toLowerCase().replace(/\s/g, '');
    str2 = str2.toLowerCase().replace(/\s/g, '');
    
    // Sort and compare
    return str1.split('').sort().join('') === 
           str2.split('').sort().join('');
}

console.log("listen & silent:", isAnagram1("listen", "silent"));
console.log("hello & world:", isAnagram1("hello", "world"));
console.log("The Morse Code & Here come dots:", 
    isAnagram1("The Morse Code", "Here come dots"));

// Method 2: Character frequency count
function isAnagram2(str1, str2) {
    str1 = str1.toLowerCase().replace(/\s/g, '');
    str2 = str2.toLowerCase().replace(/\s/g, '');
    
    if (str1.length !== str2.length) return false;
    
    let count1 = {};
    let count2 = {};
    
    // Count characters in str1
    for (let char of str1) {
        count1[char] = (count1[char] || 0) + 1;
    }
    
    // Count characters in str2
    for (let char of str2) {
        count2[char] = (count2[char] || 0) + 1;
    }
    
    // Compare counts
    for (let char in count1) {
        if (count1[char] !== count2[char]) {
            return false;
        }
    }
    
    return true;
}

console.log("\nUsing frequency:");
console.log("listen & silent:", isAnagram2("listen", "silent"));
console.log("aabb & abab:", isAnagram2("aabb", "abab"));

// Method 3: Single object count
function isAnagram3(str1, str2) {
    str1 = str1.toLowerCase().replace(/\s/g, '');
    str2 = str2.toLowerCase().replace(/\s/g, '');
    
    if (str1.length !== str2.length) return false;
    
    let count = {};
    
    // Increment for str1
    for (let char of str1) {
        count[char] = (count[char] || 0) + 1;
    }
    
    // Decrement for str2
    for (let char of str2) {
        if (!count[char]) return false;
        count[char]--;
    }
    
    return true;
}

console.log("\nSingle object:");
console.log("evil & vile:", isAnagram3("evil", "vile"));
Output
listen & silent: true
hello & world: false
The Morse Code & Here come dots: true

Using frequency:
listen & silent: true
aabb & abab: true

Single object:
evil & vile: true

Understanding Anagram Check

This program demonstrates different methods to check if two strings are anagrams.

Anagram Definition

Two strings are anagrams if:

•They contain same characters
•Same frequency of each character
•Different order

Examples:

•"listen" ↔ "silent"
•"evil" ↔ "vile"
•"The Morse Code" ↔ "Here come dots"

Method 1: Sort and Compare

Sort both strings and compare:

str1.split('').sort().join('') === 
str2.split('').sort().join('');

Steps:

1.Convert to arrays
2.Sort both
3.Join back to strings
4.Compare

Time Complexity:

O(n log n) due to sort

Method 2: Character Frequency

Count character occurrences:

let count1 = {};
for (let char of str1) {
    count1[char] = (count1[char] || 0) + 1;
}

// Compare counts

Object Counting:

•count[char] || 0: Default to 0 if undefined
•Increment count for each character

Method 3: Single Object

More efficient:

for (let char of str1) {
    count[char] = (count[char] || 0) + 1;
}


// Decrement for str2
for (let char of str2) {
    if (!count[char]) return false;
    count[char]--;
}

// Increment for str1

How it works:

•Increment counts for str1
•Decrement counts for str2
•If all become 0, they're anagrams

Time Complexity:

•Sort method: O(n log n)
•Frequency methods: O(n) - Better!

Edge Cases:

•Different lengths: Not anagrams
•Case sensitivity: Normalize with toLowerCase()
•Spaces: Remove with replace()

When to Use:

-

Sort

: Simple, readable

-

Frequency

: More efficient, handles duplicates well

Let us now understand every line and the components of the above program.

Note: To write and run JavaScript programs, you need to set up the local environment on your computer. Refer to the complete article Setting up JavaScript Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your JavaScript programs.

Practical Learning Notes for Anagram Check

This JavaScript program is part of the "String Programs" topic and is designed to help you build real problem-solving confidence, not just memorize syntax. Start by understanding the goal of the program in plain language, then trace the logic line by line with a custom input of your own. Once you can predict the output before running the code, your understanding becomes much stronger.

A reliable practice pattern is to run the original version first, then modify only one condition or variable at a time. Observe how that single change affects control flow and output. This deliberate style helps you understand loops, conditions, and data movement much faster than copying full solutions repeatedly.

For interview preparation, explain this solution in three layers: the high-level approach, the step-by-step execution, and the time-space tradeoff. If you can teach these three layers clearly, you are ready to solve close variations of this problem under time pressure.

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Count Vowels in String
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String Palindrome Check
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Count Vowels in String

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