What will be the output of the following JavaScript code?

const obj1 = { x: 5, y: 10 };
const obj2 = { ...obj1, y: 20, z: 30 };
console.log(obj2.y);

Question

What will be the output of the following JavaScript code?

const obj1 = { x: 5, y: 10 };
const obj2 = { ...obj1, y: 20, z: 30 };
console.log(obj2.y);

BlackTom AI · Accepted Answer

The question presents a JavaScript snippet involving object spread and property overrides.

First, consider the initial object: const obj1 = { x: 5, y: 10 }. This object has properties x and y with values 5 and 10 respectively.

Next, the code const obj2 = { ...obj1, y: 20, z: 30 }; uses the spread operator to copy all enumerable properties from obj1 into a new object, so at this point, obj2 would have { x: 5, y: 10 }.

After that, the code explicitly sets y: 20 within the same object literal. In JavaScript object literals, properties listed later override properties with the same key that were assigned earlier in the same object literal. Therefore, the y property that came from the spread of obj1 is overridden by the explicit y: 20, while z: 30 is added as a new property.

As a result, obj2 becomes { x: 5, y: 20, z: 30 }. When console.log(obj2.y) runs, it outputs the value of the y property, which is 20.

Note: The provided answer_options field is empty, so there are no alternative choices to evaluate in this analysis. If options were present, the analysis would compare how each one aligns with the behavior of object spreading and property overriding in object literals.

CS5610.40640.202530 Quiz 2 - React and JavaScript

What will be the output of the following JavaScript code? const obj1 = { x: 5, y: 10 }; const obj2 = { ...obj1, y: 20, z: 30 }; console.log(obj2.y);

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