52 lines
2.4 KiB
TypeScript
52 lines
2.4 KiB
TypeScript
/**
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* Merges the properties of the source object into the target object.
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*
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* You can provide a custom `merge` function to control how properties are merged. It should return the value to be set in the target object.
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*
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* If it returns `undefined`, a default deep merge will be applied for arrays and objects:
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*
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* - If a property in the source object is an array or an object and the corresponding property in the target object is also an array or object, they will be merged.
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* - If a property in the source object is undefined, it will not overwrite a defined property in the target object.
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*
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* Note that this function mutates the target object.
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*
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* @param {T} target - The target object into which the source object properties will be merged. This object is modified in place.
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* @param {S} source - The source object whose properties will be merged into the target object.
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* @param {(targetValue: any, sourceValue: any, key: string, target: T, source: S) => any} merge - A custom merge function that defines how properties should be combined. It receives the following arguments:
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* - `targetValue`: The current value of the property in the target object.
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* - `sourceValue`: The value of the property in the source object.
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* - `key`: The key of the property being merged.
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* - `target`: The target object.
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* - `source`: The source object.
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*
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* @returns {T & S} The updated target object with properties from the source object merged in.
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*
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* @template T - Type of the target object.
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* @template S - Type of the source object.
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*
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* @example
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* const target = { a: 1, b: 2 };
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* const source = { b: 3, c: 4 };
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*
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* mergeWith(target, source, (targetValue, sourceValue) => {
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* if (typeof targetValue === 'number' && typeof sourceValue === 'number') {
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* return targetValue + sourceValue;
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* }
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* });
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* // Returns { a: 1, b: 5, c: 4 }
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* @example
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* const target = { a: [1], b: [2] };
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* const source = { a: [3], b: [4] };
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*
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* const result = mergeWith(target, source, (objValue, srcValue) => {
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* if (Array.isArray(objValue)) {
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* return objValue.concat(srcValue);
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* }
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* });
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*
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* expect(result).toEqual({ a: [1, 3], b: [2, 4] });
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*/
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declare function mergeWith<T extends Record<PropertyKey, any>, S extends Record<PropertyKey, any>>(target: T, source: S, merge: (targetValue: any, sourceValue: any, key: string, target: T, source: S) => any): T & S;
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export { mergeWith };
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