I want to merge two objects without cloning or mutating one of them.
function merge(defaultOptions, userOptions) {
// userOptions should not be cloned or mutated but should get priority over defaultOptions
return res;
}
I am using lodash but _merge does not help much. Since userOptions can be huge, I want to avoid cloning it.
Note that it is alright to mutate or clone defaultOptions as it would not affect performance of my system.
What is an optimal way to do this?
You could iterate the entries of userOptions and mutate defaultOptions.
function merge(defaultOptions, userOptions) {
Object.entries(userOptions).forEach(([key, value]) => {
if (value && typeof value === 'object') merge(defaultOptions[key] = defaultOptions[key] || [], value);
else defaultOptions[key] = value;
});
return defaultOptions;
}
So, I implemented it myself and it seems to work just fine.
/**
* Custom merge function with in place merge with behaviour similar to that of _.merge.
*
* @param {object} tar target object in which the other object is to be merged
* @param {object} src source object which is to be merged
* @returns object merged object
*/
function inPlaceMerge(tar, src) {
let res = tar;
if (_.isObject(src) && _.isObject(tar)) {
_.forEach(src, (val, key) => {
res[key] = inPlaceMerge(tar[key], val);
})
} else if (src !== undefined) {
res = src;
}
return res;
}
You can use Object destructuring this solution will make a newObject with the merge of the properties of both objects.
const newObject = {
...obj1,
...obj2
}
Assuming res is an object, you can try the following
return { ...res }
