Will array memory allocation be destroyed when function ends

February 8, 2022

Just wondering if garbage collector takes care of an array returned by function. Will this function cause memory leaks if called many times?

1.    myFun = () => {
2.       let data = []
3.       for (let i=1; i<5; i++){
4.           data.push(id: i, name: 'temp')
5.       }
6.       return data
7.    }
8.    
9.    let myData1 = myFun()
10.   let myData2 = myFun()
11.   let myData3 = myFun()

so it creates three new arrays. But what the one defined in row #2?

>Solution :

But what the one defined in row #2?

That is the same exact array that is being returned. You aren’t creating six arrays total (three inside, three outside) – you’re creating three arrays total (three inside, which then get returned to the outside).

So, that array will remain un-garbage-collected as long as the returned expression remains referenceable. If your myData1, myData2, myData3 remain referenceable forever, none of the arrays will ever be garbage collected. If they become unreferenceable and nothing can continue using them, then they’ll get garbage collected – for example, if you did

(() => {
    myFun = () => {
        let data = []
        for (let i = 1; i < 5; i++) {
            data.push(id: i, name: 'temp')
        }
        return data
    }

    let myData1 = myFun()
    let myData2 = myFun()
    let myData3 = myFun()
})();

Since myData1 etc aren’t used again, and since the scope they’re declared in ends, all arrays would then be shortly garbage collected.