💾obj.mergeWith()

JS ⟩ object ⟩ built-in ⟩ Object ⟩ extension ⟩ obj.mergeWith(...sources)

💾 程式

• replit ⟩ obj.mergeWith(...sources), compare with .assignDescriptors()

• require Object extension

Object.defineProperties(Object.prototype, {

    // 🔹 other related methods omitted ...
    
    // 🔹 obj.mergeWith(...sources)
    mergeWith: {
        value: function(...sources) {

            const descriptors = {};
            
            // collect all descriptors from sources
            sources.forEach(source => {
                
                // own enumerable (string-keyed) properties -> descriptors
                source.keys.forEach(key => {
                    descriptors[key] = source.propertyDescriptor(key);
                });
        
                // own enumerable (symbol-keyed) properties -> descriptors
                source.symbols.forEach(sym => {
                    const desc = source.propertyDescriptor(sym);
                    if (desc.enumerable) descriptors[sym] = desc;
                });
        
            });
        
            // merge
            return this.defineProperties(descriptors);
        },
    },

});

💈範例

• replit, require Object extension

const source = {
  x: 1,                  // data property
  get y() { return 2 },  // accessor (getter)
};

({}).assign(source)      // { x: 1, y: 2 }
({}).mergeWith(source)   // { x: 1, y: [Getter] }

👥 相關

• compare with Object.assign()

• extending objects

• this method needs to property enumeration and deal with their attribute(s).

📘 手冊

• Object.assign() ⟩ copying accessors