Can someone explain why [1,2,3] is not the same as [1,2,3] and [1,2,3] in JavaScript? I saw this in a YouTube video and it got me curious. Are there any more interesting quirks like this in coding?
Can someone explain why [1,2,3] is not the same as [1,2,3] and [1,2,3] in JavaScript? I saw this in a YouTube video and it got me curious. Are there any more interesting quirks like this in coding?
When using the == operator, it verifies if the two operands are pointing to the same object. Even though both objects (arrays being objects) might contain the same data, they are distinct instances, resulting in the expression evaluating as false.
When using the === and == operators to compare arrays, it's important to remember that they are comparing by reference (i.e. location in memory). Essentially, this means that "they are different arrays with the same values".
One way to make this concept clearer is to give your arrays names:
const arr1 = [1, 2, 3];
const arr2 = [1, 2, 3];
console.log(arr1 === arr2);
In this case, arr1 and arr2 are not referencing the same array.
However, if you compare an array to itself, like so:
const arr = [1, 2, 3];
console.log(arr === arr);
It will return true, because it is comparing the same reference.
The reason they are not considered equal is because they do not have the same value.
When working with JavaScript, if you create an array like [1,2,3] without assigning it a name, it will just exist as a variable in memory. However, if you give it a name like 'r' and then compare r==r, it will evaluate to true because the reference to window.r is the same as the reference to itself. On the other hand, variables like window.undefinedvariable0 and window.undefinedvariable1 may look visually similar but they are actually not the same in terms of their references.
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