VDL Plugin SDK

mergeWith

Import from @varavel/vdl-plugin-sdk/utils/objects.

function mergeWith<T, S>(
   target, 
   source, 
   merge
): T & S;

Merges the properties of the source object into the target object.

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.

If it returns undefined, a default deep merge will be applied for arrays and objects:

  • 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.
  • If a property in the source object is undefined, it will not overwrite a defined property in the target object.

Note that this function mutates the target object.

Type Parameters

Type ParameterDescription
T extends Record<PropertyKey, any>Type of the target object.
S extends Record<PropertyKey, any>Type of the source object.

Parameters

ParameterTypeDescription
targetTThe target object into which the source object properties will be merged. This object is modified in place.
sourceSThe source object whose properties will be merged into the target object.
merge(targetValue, sourceValue, key, target, source) => anyA custom merge function that defines how properties should be combined. It receives the following arguments: - targetValue: The current value of the property in the target object. - sourceValue: The value of the property in the source object. - key: The key of the property being merged. - target: The target object. - source: The source object.

Returns

T & S

The updated target object with properties from the source object merged in.

Examples

const target = { a: 1, b: 2 };
const source = { b: 3, c: 4 };

mergeWith(target, source, (targetValue, sourceValue) => {
  if (typeof targetValue === 'number' && typeof sourceValue === 'number') {
    return targetValue + sourceValue;
  }
});
// Returns { a: 1, b: 5, c: 4 }

const target = { a: [1], b: [2] };
const source = { a: [3], b: [4] };

const result = mergeWith(target, source, (objValue, srcValue) => {
  if (Array.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
});

expect(result).toEqual({ a: [1, 3], b: [2, 4] });