Objects & JSON

20 Exercises Available

Object access, defaults, deep-ish patterns, JSON safe.

Safe Nested Read (optional chaining)

Function `getCity(user)` banao jo `user.address.city` return kare. Missing ho to "Unknown".

Sample Output:

getCity({address: {city: "Mumbai"}}) => "Mumbai"
getCity({address: {}}) => "Unknown"
getCity(null) => "Unknown"

View Solution

2.Medium

Pick Keys

Create a function `pick(obj, keys)` that keeps only given keys in a new object.

Sample Output:

pick({a: 1, b: 2, c: 3}, ["a", "c"]) => {a: 1, c: 3}
pick({x: 10, y: 20}, ["z"]) => {}

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3.Easy

Merge Defaults (without mutation)

Function `withDefaults(config, defaults)` banao. Config overrides defaults. New object return karo.

Sample Output:

withDefaults({b: 20}, {a: 1, b: 2}) => {a: 1, b: 20}
withDefaults({}, {x: 10}) => {x: 10}

View Solution

4.Easy

Safe JSON Parse

Create a function `safeJsonParse(str)`. Return null for invalid input.

Sample Output:

safeJsonParse('{"a":1}') => {a: 1}
safeJsonParse('invalid') => null
safeJsonParse('[1,2,3]') => [1, 2, 3]

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5.Medium

Count by Key

Given array of users `{role}`, function `countByRole(users)` banao. Output: `{ admin: 2, user: 5 }`

Sample Output:

countByRole([{role:"admin"},{role:"user"},{role:"admin"}]) => {admin: 2, user: 1}
countByRole([{role:"user"}]) => {user: 1}

View Solution

6.Easy

Omit Keys from Object

Function `omit(obj, keys)` banao jo object se specified keys remove kare. Example: omit({a: 1, b: 2, c: 3}, ["a", "c"]) => {b: 2}

Sample Output:

omit({a: 1, b: 2, c: 3}, ["a", "c"]) => {b: 2}
omit({x: 1, y: 2}, ["x"]) => {y: 2}

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7.Medium

Flatten Object (one level)

Function `flattenObject(obj)` banao jo nested object ko one level flatten kare. Example: flattenObject({a: 1, b: {c: 2}}) => {a: 1, "b.c": 2}

Sample Output:

flattenObject({a: 1, b: {c: 2}}) => {a: 1, "b.c": 2}
flattenObject({x: {y: {z: 1}}}) => {"x.y.z": 1}

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8.Hard

Deep Merge Objects

Function `deepMerge(target, source)` banao jo dono objects ko deeply merge kare. Example: deepMerge({a: 1, b: {c: 2}}, {b: {d: 3}}) => {a: 1, b: {c: 2, d: 3}}

Sample Output:

deepMerge({a: 1, b: {c: 2}}, {b: {d: 3}}) => {a: 1, b: {c: 2, d: 3}}
deepMerge({x: 1}, {x: 2}) => {x: 2}

View Solution

9.Medium

Get Nested Property Value

Function `get(obj, path, defaultValue)` banao jo nested object se property value get kare using path string. Example: get({a: {b: {c: 1}}}, "a.b.c") => 1

Sample Output:

get({a: {b: {c: 1}}}, "a.b.c") => 1
get({a: {b: 1}}, "a.b.c", "default") => "default"

View Solution

10.Hard

Set Nested Property Value

Function `set(obj, path, value)` banao jo nested object me path string se value set kare. Example: set({}, "a.b.c", 1) => {a: {b: {c: 1}}}

Sample Output:

set({}, "a.b.c", 1) => {a: {b: {c: 1}}}
set({x: 1}, "y.z", 2) => {x: 1, y: {z: 2}}

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11.Medium

Transform Object Keys

Function `transformKeys(obj, fn)` banao jo object ke sabhi keys ko transform kare. Example: transformKeys({name: "John", age: 30}, k => k.toUpperCase()) => {NAME: "John", AGE: 30}

Sample Output:

transformKeys({name: "John", age: 30}, k => k.toUpperCase()) => {NAME: "John", AGE: 30}
transformKeys({a: 1}, k => `prefix_${k}`) => {prefix_a: 1}

View Solution

12.Easy

Invert Object (key-value swap)

Function `invert(obj)` banao jo object ke keys aur values ko swap kare. Example: invert({a: 1, b: 2}) => {1: "a", 2: "b"}

Sample Output:

invert({a: 1, b: 2}) => {1: "a", 2: "b"}
invert({x: "hello"}) => {hello: "x"}

View Solution

13.Easy

Check if Object is Empty

Function `isEmpty(obj)` banao jo check kare ki object empty hai ya nahi. Example: isEmpty({}) => true, isEmpty({a: 1}) => false

Sample Output:

isEmpty({}) => true
isEmpty({a: 1}) => false
isEmpty(null) => true

View Solution

14.Easy

Map Object Values

Function `mapValues(obj, fn)` banao jo object ke sabhi values ko transform kare. Example: mapValues({a: 1, b: 2}, x => x * 2) => {a: 2, b: 4}

Sample Output:

mapValues({a: 1, b: 2}, x => x * 2) => {a: 2, b: 4}
mapValues({x: "hello"}, s => s.toUpperCase()) => {x: "HELLO"}

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15.Easy

Filter Object by Condition

Function `filterObject(obj, fn)` banao jo object ke entries ko condition ke basis par filter kare. Example: filterObject({a: 1, b: 2, c: 3}, (v, k) => v > 1) => {b: 2, c: 3}

Sample Output:

filterObject({a: 1, b: 2, c: 3}, (v, k) => v > 1) => {b: 2, c: 3}
filterObject({x: "a", y: "b"}, (v, k) => k === "x") => {x: "a"}

View Solution

16.Easy

Get Object Size (key count)

Function `objectSize(obj)` banao jo object me keys ki count return kare. Example: objectSize({a: 1, b: 2, c: 3}) => 3

Sample Output:

objectSize({a: 1, b: 2, c: 3}) => 3
objectSize({}) => 0

View Solution

17.Easy

Find Key by Value

Function `findKey(obj, value)` banao jo object me value ke corresponding key return kare. Example: findKey({a: 1, b: 2, c: 1}, 1) => "a" (first match)

Sample Output:

findKey({a: 1, b: 2, c: 1}, 1) => "a"
findKey({x: "hello"}, "hello") => "x"

View Solution

18.Medium

Sort Object by Values

Function `sortByValues(obj)` banao jo object ke entries ko values ke basis par sort kare. Example: sortByValues({a: 3, b: 1, c: 2}) => {b: 1, c: 2, a: 3}

Sample Output:

sortByValues({a: 3, b: 1, c: 2}) => {b: 1, c: 2, a: 3}
sortByValues({x: 10, y: 5}) => {y: 5, x: 10}

View Solution

19.Easy

Compare Two Objects (shallow)

Function `shallowEqual(obj1, obj2)` banao jo dono objects ko shallow compare kare. Example: shallowEqual({a: 1, b: 2}, {a: 1, b: 2}) => true

Sample Output:

shallowEqual({a: 1, b: 2}, {a: 1, b: 2}) => true
shallowEqual({a: 1}, {a: 2}) => false

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20.Easy

Create Object from Array of Pairs

Function `fromPairs(pairs)` banao jo array of [key, value] pairs se object create kare. Example: fromPairs([["a", 1], ["b", 2]]) => {a: 1, b: 2}

Sample Output:

fromPairs([["a", 1], ["b", 2]]) => {a: 1, b: 2}
fromPairs([["x", "hello"]]) => {x: "hello"}

View Solution

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