@wordpress/editor/src/utils/set-nested-value.js

Enhanced block editor for WordPress posts.

/**
 * Sets the value at path of object.
 * If a portion of path doesn’t exist, it’s created.
 * Arrays are created for missing index properties while objects are created
 * for all other missing properties.
 *
 * This function intentionally mutates the input object.
 *
 * Inspired by _.set().
 *
 * @see https://lodash.com/docs/4.17.15#set
 *
 * @todo Needs to be deduplicated with its copy in `@wordpress/core-data`.
 *
 * @param {Object} object Object to modify
 * @param {Array}  path   Path of the property to set.
 * @param {*}      value  Value to set.
 */
export default function setNestedValue( object, path, value ) {
	if ( ! object || typeof object !== 'object' ) {
		return object;
	}

	path.reduce( ( acc, key, idx ) => {
		if ( acc[ key ] === undefined ) {
			if ( Number.isInteger( path[ idx + 1 ] ) ) {
				acc[ key ] = [];
			} else {
				acc[ key ] = {};
			}
		}
		if ( idx === path.length - 1 ) {
			acc[ key ] = value;
		}
		return acc[ key ];
	}, object );

	return object;
}