Source: \defaults.js
import eq from './eq.js'
import baseKeysIn from './.internal/baseKeysIn.js'
/** Used for built-in method references. */
const objectProto = Object.prototype
/** Used to check objects for own properties. */
const hasOwnProperty = objectProto.hasOwnProperty
/**
* Assigns own and inherited enumerable string keyed properties of source
* objects to the destination object for all destination properties that
* resolve to `undefined`. Source objects are applied from left to right.
* Once a property is set, additional values of the same property are ignored.
*
* **Note:** This method mutates `object`.
*
* @since 0.1.0
* @category Object
* @param {Object} object The destination object.
* @param {...Object} [sources] The source objects.
* @returns {Object} Returns `object`.
* @see defaultsDeep
* @example
*
* defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 })
* // => { 'a': 1, 'b': 2 }
*/
function defaults(object, ...sources) {
object = Object(object)
let srcIndex = -1
const srcLength = sources.length
while (++srcIndex < srcLength) {
const source = sources[srcIndex]
const props = baseKeysIn(source)
let propsIndex = -1
const propsLength = props.length
while (++propsIndex < propsLength) {
const key = props[propsIndex]
const value = object[key]
if (value === undefined ||
(eq(value, objectProto[key]) && !hasOwnProperty.call(object, key))) {
object[key] = source[key]
}
}
}
return object
}
export default defaults