mapObj

Same as Array.prototype.map, but for objects.

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/**
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 * Same as Array.prototype.map, but for objects.
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 **/
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const mapObj = <T, U>(
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  obj: Record<string, T>,
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  callback: (value: T, key: string, obj: Record<string, T>) => U,
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): Record<string, U> => {
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  const result: Record<string, U> = {};
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  // loop through each key in the object
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  for (const key in obj) {
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    // check if the key is a property of the object
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    if (Object.prototype.hasOwnProperty.call(obj, key)) {
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      result[key] = callback(obj[key], key, obj);
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    }
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  }
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  return result;
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};
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export default mapObj;

1. Installtion

npx @jrtilak/lazykit add mapObj

2. Parameters

  • obj (Record<string, T>)
    An object whose properties will be transformed.

  • callback ((value: T, key: string, obj: Record<string, T>) => U)
    A function that is called for each property in the object. It receives the property value, the property key, and the entire object as arguments, returning the transformed value.

3. Returns

  • Record<string, U>
    A new object with the same keys as the input object, but with values transformed by the callback function.

4. Example Usage

1. Basic Example

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import mapObj from "@/helpers/mapObj";
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const originalObject = {
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  name: "John",
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  age: 30,
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  city: "New York",
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};
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const transformedObject = mapObj(originalObject, (value, key) => {
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  return typeof value === "number" ? value * 2 : value.toUpperCase();
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});
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console.log(transformedObject); 
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// Output: { name: "JOHN", age: 60, city: "NEW YORK" }

2. With Nested Objects

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import mapObj from "@/helpers/mapObj";
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const data = {
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  alice: {
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    age: 28,
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  },
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  los: {
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    age: 50,
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  },
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};
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const ages = mapObj(data, (value) => {
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  return value.age;
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});
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console.log(ages); 
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// Output: { alice: 28, los: 50 }