(JavaScript) Synchronizing forEach Loop with callbacks inside

Question

I am doing some computations inside a double forEach Loop something like this:

array.forEach(function(element){
    Object.keys(element).forEach         


        

Answer 1

For browsers which support Promise (or using polyfill) / nodejs I've implemented my self a sync version of forEach with callbacks, so I'll just share that here..

The callback must return a promise..

function forEachSync(array, callback) {
    let lastIndex = array.length - 1;
    let startIndex = 0;

    return new Promise((resolve, reject) => { // Finish all
        let functionToIterateWith = (currIndex) => {
            if (currIndex > lastIndex) {
                return resolve();
            } else {
                callback(array[currIndex]).then(() => {
                    functionToIterateWith(currIndex + 1);
                }).catch(err => reject(err));
            }
        }

        functionToIterateWith(startIndex);
    });
}