Syntax, Parameter and Return Value
Syntax:
_.assign(target, ...sources)
Parameters:
-
target (Object): The destination object.
- ...sources (Object): The source objects.
Return Value:
(Object) - Returns the modified target object.
Examples
Basic Object Merging:
JavaScript
var _ = require('lodash');
var object = { 'a': 1 };
var other = { 'b': 2 };
_.assign(object, other);
console.log(object);
You can also try this code with Online Javascript Compiler
Output:
{ 'a': 1, 'b': 2 }
Demonstrates merging two objects into one.
Merging Multiple Objects:
JavaScript
var defaults = { a: 1, b: 2 };
var config = { b: 3, c: 4 };
var options = { c: 5 };
var result = _.assign({}, defaults, config, options);
console.log(result);
You can also try this code with Online Javascript Compiler
Output:
{ a: 1, b: 3, c: 5 }
Shows how to merge multiple objects, combining and overriding properties.
Updating Object Properties:
JavaScript
var state = { loading: false, data: null };
var newState = _.assign({}, state, { loading: true, data: { items: [] }});
console.log(newState);
You can also try this code with Online Javascript Compiler
Output:
{ loading: true, data: { items: [] }}
An example of using _.assign() to update properties in a state object.
Extending Object with Additional Properties:
JavaScript
var user = { name: 'John Doe' };
var additionalInfo = { age: 30, occupation: 'Developer' };
_.assign(user, additionalInfo);
console.log(user);
You can also try this code with Online Javascript Compiler
Output:
{ name: 'John Doe', age: 30, occupation: 'Developer' }
Demonstrates extending an object with additional properties from another object.
Frequently Asked Questions
How does _.assign() differ from Object.assign() in JavaScript?
_.assign() and Object.assign() perform similarly in that they copy properties from source objects to a target object. However, _.assign() works well with Lodash's utility-first approach and chaining capabilities.
Does _.assign() perform deep cloning?
No, _.assign() performs a shallow copy of properties. It does not clone nested objects but rather copies their references.
What happens if there are property conflicts?
If source objects have the same property, _.assign() will overwrite the property in the target object with the last source's value for that property.
Conclusion
Lodash's _.assign() method is a powerful tool for merging properties from one or more source objects into a target object. It is especially useful for object composition, updating states, or extending configurations in a clear and readable manner.
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