Object Spread vs. Object.assign(): When Should You Choose Which?

Object Spread vs. Object.assign: Performance and Functionality Considerations

When working with objects in JavaScript, two commonly used methods for combining and manipulating them are object spread syntax ({...}) and the Object.assign() method. Understanding the advantages and drawbacks of each approach is crucial for efficient and effective code development.

Object Spread Syntax ( {...} )

• Advantages:

  • Less verbose
  • Supports direct compilation in certain environments without the need for polyfills

• Disadvantages:

  • Literal and not dynamic
  • May require polyfills for older browsers or non-standard environments

Object.assign() Method

• Advantages:

  • Standardized and widely supported
  • Dynamic, allowing for more flexible object manipulation

• Disadvantages:

  • More verbose
  • Requires polyfills for environments without native support

Consider the following examples:

Setting Default Options

<code class="javascript">options = {...optionsDefault, ...options}; // Object spread syntax</code>

<code class="javascript">options = Object.assign({}, optionsDefault, options); // Object.assign() method</code>

Both methods achieve the same result of merging the optionsDefault and options objects. However, the spread syntax offers a more concise approach.

Dynamic Object Creation

<code class="javascript">var sources = [{a: "A"}, {b: "B"}, {c: "C"}];
// Using Object spread syntax
options = {...sources};

// Using Object.assign() method and apply()
options = Object.assign.apply(Object, [{}].concat(sources));

// Using Object.assign() method and rest spread
options = Object.assign({}, ...sources);</code>

The Object.assign() method allows for dynamic object creation based on an arbitrary number of source objects. The spread syntax used in the second and third examples collapses the source array into a list of arguments, making it a more flexible option.

Performance Considerations

Performance benchmarks indicate that Object.assign() is generally faster than object spread syntax. However, the performance gap may vary depending on the environment and browser.

Conclusion

When choosing between object spread syntax and Object.assign(), consider the following factors:

• Verbosity: Object spread is more concise, while Object.assign() is more verbose.
• Dynamic nature: Object.assign() allows for dynamic object creation and manipulation.
• Standardization: Object.assign() is a standardized method, while spread syntax is relatively recent and may require transpilation or polyfills in certain environments.
• Performance: Object.assign() is generally faster, but the performance impact may vary across environments.

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