Combining Multiple Objects
Consider you have three different objects:const obj1 = {'No': 1, 'firstname': 'Rakesh'};
const obj2 = {'lastname': 'Patel'};
const obj3 = {'Sex': 'Male','progLang':['.Net','MVC','SharePoint']};
combine all the above 3 object into another object:
const objCombined = {...obj1, ...obj2, ...obj3};
The '…' is the spread operator. You can read more about this in the MDN Web Docs
Check if an object is an array
const obj = {data: 1};const arr = [1, 2, 3];
Array.isArray(obj); // false
Array.isArray(arr); // true
Rest parameter syntax
A function that accepts any number of arguments. There is a special syntax called the rest parameter syntax to create such a function.Example 1:
function test(...values) {console.log(values);
}
test(1);
test(1, 2);
test(1, 2, 3);
test(1, 2, 3, 4);
output:
[1]
[1, 2]
[1, 2, 3]
[1, 2, 3, 4]
you can even pass object as a arguments
Example 2:
function sum(...values) {let sum = 0;
for (let i = 0; i < values.length; i++) {
sum += values[i];
}
return sum;
}
console.log(sum(1));
console.log(sum(1, 2));
console.log(sum(1, 2, 3));
console.log(sum(1, 2, 3, 4));
output:
1
3
6
10
