What is the best way in nodejs to compare two different array of objects based on one or more attributes/fields? The fields name can be different - node.js

Question

let obj1 = [{field1:11, field2:12, field3:13}, {field1:21, field2:22, field3:23}, {field1:31, field2:32, field3:33}, {field1:41, field2:42, field3:43}];
let obj2 = [{attribute1:21, attribute2:22}, {attribute1:31, attribute2:32}, {attribute1:11, attribute2:12}];
let output = [];
obj1.map(o1 => {
for (let i=0;i<obj2.length;i++) {
if (o1.field1 === obj2[i].attribute1) {
output.push(Object.assign(obj2[i], o1));
obj2.splice(i,1);
break;
}
}
});
console.log(output); //*[{attribute1:11,attribute2:12,field1:11,field2:12,field3:13},{attribute1:21,attribute2:22,field1:21,field2:22,field3:23},{attribute1:31,attribute2:32,field1:31,field2:32,field3:33}]*
The above code compares two different objects with its fields.
Here I am using 2 loops.
So my question is, do we have any better approach to achieve the same? Without two loops or using any package or the best way

Answer 1

You can use find to find the first element where the statement is true instead of looping and manually checking if the statement is true or false. Sadly find is also an iterative method but I don't see any other way to improve this. I am using filter to remove the elements that don't fulfil the condition o2.attribute1 === o1.field1.
let obj1 = [{field1:11, field2:12, field3:13}, {field1:21, field2:22, field3:23}, {field1:31, field2:32, field3:33}, {field1:41, field2:42, field3:43}];
let obj2 = [{attribute1:21, attribute2:22}, {attribute1:31, attribute2:32}, {attribute1:11, attribute2:12}];
const output = obj1.map(o1 => {
let obj2Value = obj2.find(o2 => o2.attribute1 === o1.field1);
return obj2Value ? Object.assign(obj2Value, o1) : null;
}).filter(o => o !== null);
console.log(output);
Alternatively you can use forEach to do this:
let obj1 = [{field1:11, field2:12, field3:13}, {field1:21, field2:22, field3:23}, {field1:31, field2:32, field3:33}, {field1:41, field2:42, field3:43}];
let obj2 = [{attribute1:21, attribute2:22}, {attribute1:31, attribute2:32}, {attribute1:11, attribute2:12}];
let output = [];
obj1.forEach(o1 => {
let obj2Value = obj2.find(o2 => o2.attribute1 === o1.field1);
obj2Value ? output.push(Object.assign(obj2Value, o1)) : '';
});
console.log(output);
There are several approaches to achieve this. Also remember map already returns a new array so no need to use push inside, just return. Check this for better understanding:
https://stackoverflow.com/questions/34426458/javascript-difference-between-foreach-and-map#:~:text=forEach%20%E2%80%9Cexecutes%20a%20provided%20function,every%20element%20in%20this%20array.%E2%80%9D .