Destructuring with nested objects and default values
This example will help you to understand the destructing of array
and object
with fallback values.
You can use the =
symbol for adding fallback
or default
value while destructing.
const person = {
firstName: 'Nikhil',
address: {
city: 'Dhule',
state: 'MH'
},
/*children: [
{
name: 'Ninu',
age: 3
}
]*/
}
const {
firstName,
address: {
city,
state
},
children: {
0: {
name='Oshin' // Fallback for name is string i.e 'Oshin'
}={} // Fallback for 1st index value of array is blank object
}=[] // Fallback for children is blank array
} = person;
console.log(`${firstName} is from ${city} and his first child name is ${name}`);
The above code will not work if the object does not have c in it
const { a, b, c: { e = 'default', f = 'default'}} = {a: 1, b: 2}
console.log(`a: ${a}, b: ${b}, e: ${e}, f: ${f}`)
const { a, b, c: { e = 'default', f = 'default'} ={} } = {a: 1, b: 2}
console.log(`a: ${a}, b: ${b}, e: ${e}, f: ${f}`)
Just replace =
with :
:
const {a, b, c: {e = 'default', f = 'default'}} = require('./something')
Demo:
const { a, b, c: { e = 'default', f = 'default'} } = {a: 1, b: 2, c: {e: 3}}
console.log(`a: ${a}, b: ${b}, e: ${e}, f: ${f}`)
It prints:
a: 1, b: 2, e: 3, f: default