Assume there are two arrays like this:
const element = ['abc', 'def']`
const total = [
{ _id: 'foo', something: 'else' }
{ _id: 'abc' },
{ _id: 'bar' },
{ _id: 'def' }
]
I need to find the element items in the total array and return the index value. So the result should be
[1, 3]
I thought of using a loop and look up with indexOf, but that is not the correct way:
element.forEach(e => {
total.indexOf(e)
})
Your original test of total.indexOf(e) doesn't search for the object with its _id property value being e - it searches for whether the object equals the 'abc' or 'def' string, which is of course never true.
Instead, you can use reduce:
const element = ['abc', 'def'];
const total = [
{ _id: 'foo', something: 'else' },
{ _id: 'abc' },
{ _id: 'bar' },
{ _id: 'def' }
];
const foundIndicies = total.reduce((a, { _id }, i) => {
if (element.includes(_id)) a.push(i);
return a;
}, []);
console.log(foundIndicies);
You can map over element with a variable e, and use Array.prototype.findIndex() on the total array to find the index of the first dictionary that contains e as one of its values, which you can retrieve using Object.values:
const element = ['abc', 'def'];
const total = [
{ _id: 'foo', something: 'else' },
{ _id: 'abc' },
{ _id: 'bar' },
{ _id: 'def' }
];
const locations = element.map(e => total.findIndex(d => Object.values(d).includes(e)))
console.log(locations);