console. Log() is an asynchronous operation???

The above code , look consol.log() It's like executing asynchronously , But it's not . It's because when you click the expand button on the console , The browser will go to get the latest result Value . therefore result[0].a === 2

Just change it to the following , You can prove it ！

var obj = { a: 1 };
var oldArray = [obj];
var result = oldArray.concat([1,2]);
// debugger
console.log(result[0].a);
obj.a = 2;
console.log(result[0].a);

Reference material ：console.log Is an asynchronous flow ？ I feel like I stepped on a pit - SegmentFault Think no