how to use the assignwith function from lodash in javascript

The _.assignWith() function from the Lodash library is used to assign values from one or more source objects to a destination object. It allows you to provide a custom function for resolving conflicts between source and destination object values.

Here's an example of how to use assignWith:

index.tsx
const _ = require('lodash');

const customizer = (objValue, srcValue) => {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
};

const objA = {
  foo: [1, 2, 3],
  bar: { a: 1, b: 2 }
};

const objB = {
  foo: [4, 5],
  bar: { b: 3, c: 4 }
};

const result = _.assignWith({}, objA, objB, customizer);

console.log(result);
// Output:
// {
//   foo: [1, 2, 3, 4, 5],
//   bar: { a: 1, b: 3, c: 4 }
// }
423 chars
27 lines

In this example, we're using assignWith to merge objA and objB into a new object. We've provided a custom function customizer that takes the object value from objA and the source value from objB as arguments. If the value is an array, we want to concatenate the values from objA and objB into a single array. Otherwise, we'll let assignWith use its default behavior.

The output shows that assignWith has merged the two objects using our customizer function, resulting in a new object with concatenated arrays and merged objects.