merge

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2023-12-01

Produces an ObjectLikeSequence consisting of all the recursively merged values from this and the given object(s) or sequence(s).

Note that by default this method only merges "vanilla" objects (bags of key/value pairs), not arrays or any other custom object types. To customize how merging works, you can provide the mergeFn argument, e.g. to handling merging arrays, strings, or other types of objects.

Signature

ObjectLikeSequence.merge = function(others, mergeFn) { /*...*/ }

ObjectLikeSequence.merge = function merge(var_args) {
  var mergeFn = arguments.length > 1 && typeof arguments[arguments.length - 1] === "function" ?
arrayPop.call(arguments) : null;
  return new MergedSequence(this, arraySlice.call(arguments, 0), mergeFn);
}

Name	Type(s)	Description
others	...Object\|ObjectLikeSequence	The other object(s) or sequence(s) whose values will be merged into this one.
mergeFn	Function?	An optional function used to customize merging behavior. The function should take two values as parameters and return whatever the "merged" form of those values is. If the function returns undefined then the new value will simply replace the old one in the final result.
returns	ObjectLikeSequence	The new sequence consisting of merged values.

Examples

// These examples are completely stolen from Lo-Dash's documentation:
// lodash.com/docs#merge

var names = {
  'characters': [
{ 'name': 'barney' },
{ 'name': 'fred' }
  ]
};

var ages = {
  'characters': [
{ 'age': 36 },
{ 'age': 40 }
  ]
};

var food = {
  'fruits': ['apple'],
  'vegetables': ['beet']
};

var otherFood = {
  'fruits': ['banana'],
  'vegetables': ['carrot']
};

function mergeArrays(a, b) {
  return Array.isArray(a) ? a.concat(b) : undefined;
}

Lazy(names).merge(ages); // => sequence: { 'characters': [{ 'name': 'barney', 'age': 36 }, { 'name': 'fred', 'age': 40 }] }
Lazy(food).merge(otherFood, mergeArrays); // => sequence: { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }

// ----- Now for my own tests: -----

// merges objects
Lazy({ foo: 1 }).merge({ foo: 2 }); // => sequence: { foo: 2 }
Lazy({ foo: 1 }).merge({ bar: 2 }); // => sequence: { foo: 1, bar: 2 }

// goes deep
Lazy({ foo: { bar: 1 } }).merge({ foo: { bar: 2 } }); // => sequence: { foo: { bar: 2 } }
Lazy({ foo: { bar: 1 } }).merge({ foo: { baz: 2 } }); // => sequence: { foo: { bar: 1, baz: 2 } }
Lazy({ foo: { bar: 1 } }).merge({ foo: { baz: 2 } }); // => sequence: { foo: { bar: 1, baz: 2 } }

// gives precedence to later sources
Lazy({ foo: 1 }).merge({ bar: 2 }, { bar: 3 }); // => sequence: { foo: 1, bar: 3 }

// undefined gets passed over
Lazy({ foo: 1 }).merge({ foo: undefined }); // => sequence: { foo: 1 }

// null doesn't get passed over
Lazy({ foo: 1 }).merge({ foo: null }); // => sequence: { foo: null }

// array contents get merged as well
Lazy({ foo: [{ bar: 1 }] }).merge({ foo: [{ baz: 2 }] }); // => sequence: { foo: [{ bar: 1, baz: 2}] }