Checking for the similarity of two 2-D arrays in JavaScript

We are required to write a JavaScript function that takes in two 2-D arrays and returns a boolean based on the check whether the arrays are equal or not. The equality of these arrays, in our case, is determined by the equality of corresponding elements.

Both the arrays should have same number of rows and columns. Also, arr1[i][j] === arr2[i][j] should yield true for all i between [0, number of rows] and j between [0, number of columns]

Method 1: Basic Nested Loop Approach

This method compares each element position by position using nested loops:

const arr1 = [
    [1, 1, 1],
    [2, 2, 2],
    [3, 3, 3],
];
const arr2 = [
    [1, 1, 1],
    [2, 2, 2],
    [3, 3, 3],
];

const areEqual = (first, second) => {
    const { length: l1 } = first;
    const { length: l2 } = second;
    
    if(l1 !== l2){
        return false;
    }
    
    for(let i = 0; i < l1; i++){
        // Check if row lengths are equal
        if(first[i].length !== second[i].length){
            return false;
        }
        
        for(let j = 0; j < first[i].length; j++){
            if(first[i][j] !== second[i][j]){
                return false;
            }
        }
    }
    return true;
};

console.log(areEqual(arr1, arr2));

true

Method 2: Using JSON.stringify

A simpler approach converts both arrays to JSON strings for comparison:

const arr3 = [[1, 2], [3, 4]];
const arr4 = [[1, 2], [3, 4]];
const arr5 = [[1, 2], [3, 5]];

const areEqualJSON = (first, second) => {
    return JSON.stringify(first) === JSON.stringify(second);
};

console.log(areEqualJSON(arr3, arr4)); // Same arrays
console.log(areEqualJSON(arr3, arr5)); // Different arrays

true
false

Testing with Different Cases

Let's test our function with various scenarios:

// Different dimensions
const diffRows = [[1, 2], [3, 4]];
const moreRows = [[1, 2], [3, 4], [5, 6]];

// Different column lengths
const jaggedArr1 = [[1, 2, 3], [4, 5]];
const jaggedArr2 = [[1, 2, 3], [4, 5, 6]];

console.log("Different row count:", areEqual(diffRows, moreRows));
console.log("Different column lengths:", areEqual(jaggedArr1, jaggedArr2));
console.log("Empty arrays:", areEqual([], []));

Different row count: false
Different column lengths: false
Empty arrays: true

Comparison of Methods

Conclusion

Both methods effectively compare 2-D arrays. Use nested loops for better performance with large datasets, or JSON.stringify for simpler code when performance isn't critical.