如何在异步函数中访问双嵌套数组中的数据 - javascript？

Question

I've got array which has another array which contains data i need.

How do i access "0x88def628c16651eb0d86be5ead3d738d0cb27fe947bb786c23105ac5d67a1bd0" in javascript for example? This is being displayed by calling var transakcije.

I've tried with:

transakcije[0][0] but that is not the name of sub array,

transakcije[0],

for loop (transakcija as transakcije) to no avail.

I've searched familiar answers but found none to my aid. I appreciate any help i recieve. Below is var transakcije being displayed in console.log().

---

---

function getBlockchainTransactions(blockNumber){
    var tx = [];
    return new Promise(resolve => {
        for(var i=0; i<blockNumber; i++){
            web3.eth.getBlock(i, function(error, block){
            if(!error && block.transactions.length != 0){
                console.log(block.transactions);
                tx.push(block.transactions);
            }
        })
        }
            resolve(tx);
    });

}


async function msg() {
    const transakcije = await getBlockchainTransactions(blockNumber);
    console.log(transakcije);
}

Answer 1

getBlock is async, hence you are resolving an empty array because for loops in javascript are synchronous, but you're using an async callback inside them, and resolve is called before tx.push is.

I would suggest you a recursive async approach, like this:

function getBlockchainTransactions(blockNumber){
    var tx = [];
    return new Promise(resolve => {
            // declare a recrusive async loop.
         var recursiveAsyncLoop = function(current, max) {
            // If the current index is exactly blockNumber, resolve.
          if (current === max) {
            resolve(tx);
          }
          // Otherwise, excute the operation on the actual block.
          else {
            var i = current;
            web3.eth.getBlock(i, function(error, block){
              if(!error && block.transactions.length != 0){
                console.log(block.transactions);
                tx.push(block.transactions);
                // once the operation is finished, increase the counter on the next call.
                recursiveAsyncLoop(current + 1, max);
              }
              // In cany case, regardless the above is true or false, continue.
              else recursiveAsyncLoop(current + 1, max);
            })
          }
         }
         // Begin the loop, from index 0 until blockNumber (excluded).
         recursiveAsyncLoop(0, blockNumber);
    });

}


async function msg() {
    const transakcije = await getBlockchainTransactions(blockNumber);
    console.log(transakcije);
}

The above code should call resolve only when the items are effectively added to the array.