i have this
arr = [{name: 'pippo',lastname: 'p'},{name: 'mickey',lastname: 'mouse'}]
x ={name: 'mickey', lastname: 'mouse'}
arr.indexOf(x)why arr.indexOf(x) returning -1? Is there another solution to find the index of an object inside of an array of objects?
Since you have array of objects, it does not work straight forward using indexOf() to get the index of that specific object in that array. You need to use findIndex() so that when there is a matching object in the array, it returns the respective index of that object, else -1.
arr = [{name: 'pippo',lastname: 'p'},{name: 'mickey',lastname: 'mouse'}]
x ={name: 'mickey', lastname: 'mouse'}
console.log(arr.findIndex((obj) => obj.name == x.name && obj.lastname === x.lastname));
indexOf() checks the reference of the object inside the array. Since you are making a new object and passing it as an argument to indexOf() it doesn't match the reference of object inside the array so it fails.
let arr = [{name: 'pippo',lastname: 'p'},{name: 'mickey',lastname: 'mouse'}]
arr.indexOf(arr[1])
Whereas this code will return 1 as expected as the reference is same.
Solution as given by @Ankit
arr = [{name: 'pippo',lastname: 'p'},{name: 'mickey',lastname: 'mouse'}]
x ={name: 'mickey', lastname: 'mouse'}
console.log(arr.findIndex((obj) => obj.name == x.name && obj.lastname === x.lastname));
Using simple loop
arr = [{name: 'pippo',lastname: 'p'},{name: 'mickey',lastname: 'mouse'}]
x ={name: 'mickey', lastname: 'mouse'}
for(let i=0;i< arr.length;i++){
if(JSON.stringify(arr[i])===JSON.stringify(x))
console.log(i)
}