Searching objects by value in JavaScript

When working with complex JavaScript objects, you often need to find all keys that contain a specific value. This is particularly useful for nested objects where the same value might appear at multiple levels.

Consider this example object with nested structure:

const obj = {
    "name": "Vivek Sharma",
    "occupation": "Software Engineer",
    "age": 23,
    "contacts": [{
        "name": "Mukul Sharma",
        "occupation": "Software Engineer",
        "age": 31,
    }, {
        "name": "Jay Sharma",
        "occupation": "Software Engineer",
        "age": 27,
    }, {
        "name": "Rajan Sharma",
        "occupation": "Software Engineer",
        "age": 32,
    }]
};

console.log("Original object:", JSON.stringify(obj, null, 2));

Original object: {
  "name": "Vivek Sharma",
  "occupation": "Software Engineer",
  "age": 23,
  "contacts": [
    {
      "name": "Mukul Sharma",
      "occupation": "Software Engineer",
      "age": 31
    },
    {
      "name": "Jay Sharma",
      "occupation": "Software Engineer",
      "age": 27
    },
    {
      "name": "Rajan Sharma",
      "occupation": "Software Engineer",
      "age": 32
    }
  ]
}

Creating the keysOf Method

We'll create a prototype method that searches through nested objects and returns all keys containing a specific value:

const keysOf = function(val, obj = this, res = []) {
    const keys = Object.keys(obj);
    
    for (let ind = 0; ind 

Example Usage

const obj = {
    "name": "Vivek Sharma",
    "occupation": "Software Engineer",
    "age": 23,
    "contacts": [{
        "name": "Mukul Sharma",
        "occupation": "Software Engineer",
        "age": 31,
    }, {
        "name": "Jay Sharma",
        "occupation": "Software Engineer",
        "age": 27,
    }, {
        "name": "Rajan Sharma",
        "occupation": "Software Engineer",
        "age": 32,
    }]
};

const keysOf = function(val, obj = this, res = []) {
    const keys = Object.keys(obj);
    
    for (let ind = 0; ind 

Keys with value 23: ['age']
Keys with value 'Software Engineer': ['occupation']
Keys with value 'Vivek Sharma': ['name']


How It Works

The algorithm uses recursive traversal:

• Base case: If a value matches exactly, add the key to results
• Recursive case: If the value is a non-null, non-array object, search deeper
• Accumulator: The res array collects all matching keys across all levels

Alternative Implementation

Here's a standalone function approach without modifying the prototype:

function findKeysByValue(obj, searchValue, currentPath = []) {
    const results = [];
    
    for (const [key, value] of Object.entries(obj)) {
        if (value === searchValue) {
            results.push(key);
        } else if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
            results.push(...findKeysByValue(value, searchValue, [...currentPath, key]));
        }
    }
    
    return results;
}

const testObj = {
    name: "John",
    age: 30,
    details: {
        age: 30,
        city: "New York"
    }
};

console.log("Keys with value 30:", findKeysByValue(testObj, 30));
console.log("Keys with value 'John':", findKeysByValue(testObj, "John"));

Keys with value 30: ['age', 'age']
Keys with value 'John': ['name']

Conclusion

Searching objects by value requires recursive traversal for nested structures. The keysOf method provides an efficient way to find all keys containing a specific value across multiple object levels.