Object spread vs. Object.assign

Peel the onion: A detailed evaluation of Spread and Object.assign()

Spread and Object.assign(): By the book

Spread syntax and Object.assign() are both handy for merging objects. The spread syntax is an ES2018 standard, maintaining object integrity without copying prototype attributes. It gives a shallow copy and does not invoke setters, unlike Object.assign(). On the flip side, Object.assign() is more versatile, modifies, and returns the same object, luring those who value prototype preservation.

Performance part of the equation

Both need Babel for legacy environments with Object.assign() in need of a polyfill - just a few extra bytes. After desugaring and Babel compiling, spread syntax produces similar bytecode to Object.assign({}). With the spread operator being more laconic, Object.assign() steals the show in runtime efficiency and is preferred when handling computed properties — a Vue.js takeaway.

Picking patterns: Dev preferences and practical usage

Developers cherish code patterns and often favor user code over dependencies. It's crucial to respect this sentiment when looking at non-standardized proposals, especially during GitHub contributions. On the error objects subject, when mutating instance variables, Object.assign() tends to be the go-to, as it allows explicit control over property enumeration and attribution.

Digging deeper: Advanced scenarios and quirks

When handling immutable objects, set immutable properties regardless of the copying method for a smooth sailing experience. Pay heed to the varying behaviour of spread and Object.assign() in arrays and objects.

Computed properties and functions combo: Dive in

While spread syntax restricts itself to literals, Object.assign() can be dynamic and team up with apply() or directly spread on sources; thus dealing with computed property names is a breeze.

let propName = 'dynamicKey';
let value = 5;

// For those who remember playing hide and seek with computed properties
const combinedWithComputed = { ...{ staticKey: 'static' }, [propName]: value }; // Spread with computed 

// Ready to juggle those mysterious computed properties, right? 
const assignedWithComputed = Object.assign({}, { staticKey: 'static' }, { [propName]: value }); // Object.assign with computed
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Vue.js corner: Specific cases

In Vue.js, Vue.set() comes as a best practice for reactivity tracking, compared to Object.assign() in Vue 2. Regarding computed function efficiency, Object.assign() is the preferred guest due to Vue's reactivity system optimizations.

Undiscovered territories: Spread limitations

Using spread operator in nested objects comes with a caveat: it provides shallow copies, so toy with nested properties carefully lest you risk the integrity of the original object.

State of the art integration: Present-day tools

Both Object.assign() and spread integrate effortlessly with modern JavaScript tools like webpack and Babel. Double-check the compilation output for efficiency post-transpilation.

Tool belt ready: Aligning with best practices

Your specific use case and legacy support appraisal dictate the apt copying method. Align with the best practices and the current JS spec from the get-go.