how to use the defaultsdeep function from lodash in javascript

The defaultsDeep() function from lodash provides a convenient way to merge two or more objects while allowing for nested properties to be merged deeply.

Here is an example of how to use defaultsDeep() in JavaScript:

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

const defaultSettings = {
  port: 3000,
  database: {
    host: 'localhost',
    name: 'my-app-db',
    user: 'root',
    password: 'password123'
  },
  logging: true
};

const userSettings = {
  port: 8080,
  database: {
    name: 'user-db',
    user: 'user',
  },
  logging: false,
  timezone: 'UTC'
};

const finalSettings = _.defaultsDeep({}, userSettings, defaultSettings);

console.log(finalSettings);
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In the code above, we first require the lodash library. We then define two objects defaultSettings and userSettings. We want to merge the two objects so that any properties defined in defaultSettings but not in userSettings are added to userSettings, but with nested properties merged deeply.

To accomplish this, we call _.defaultsDeep() with three arguments. The first argument is an empty object {} which serves as the destination for the merged properties. The second argument is the object that we want to merge into the destination object, in this case userSettings. The third argument is the object that we want to merge into the destination object, in this case defaultSettings.

After calling the _.defaultsDeep() function, we log the final merged settings object to the console which should output the following:

index.tsx
{
  port: 8080,
  database: {
    host: 'localhost',
    name: 'user-db',
    user: 'user',
    password: 'password123'
  },
  logging: false,
  timezone: 'UTC'
}
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Notice that the properties from userSettings take precedence over those from defaultSettings and that nested properties are correctly merged.