foreach-promise

handle series of nested forEachs as one big promise

If you are tired of handling js asynchronous forEachs with counters and stuff, this little module will help you.

Install

npm install foreach-promise --save

Usage

 const forEP = require('foreach-promise');
 
 forEP(array, callback) : returns a Promise that resolves when all the data is traversed
 callback can be a function which returns another forEP execution. (for foreach nesting)
 callback will be called with element, index, array arguments.

Let's say you're coding a function to generate names with nouns and adjectives, maybe you code something like the function below to do this.

function createNames(nouns, adjectives){

    const namesList = [];

    return new Promise( (resolve, reject) => {
        let nounsLen = nouns.length;
        nouns.forEach(function(n){

            let adjLen = adjectives.length;
            adjectives.forEach(function(ad){

                namesList.push( ad + " " + n );
                
                //resolve this promise with the built namesList
                //the conditional below is to make sure my Promise only will resolve when all data is processed
                if(--nounsLen <= 0 && --adjLen <= 0){
                    resolve(namesList);
                }

            });
        });

    });

}

But you really dont wanna do this everytime you need some data manipulation like this.

And this can be a mess as the number of nested forEachs increases.

So, through this module, which I call: foreach-promise , you can implement the function above like the code below:

const forEP = require('foreach-promise');
function createNames(nouns, adjectives){

    const namesList = [];

    return new Promise( (resolve, reject) => {
        forEP(nouns, (n, index, array)=> {
            return forEP(adjectives, (ad, index, array)=>{ //for nested forEP, we should return a promise. and forEP returns that promise.
                namesList.push( ad + " " + n ); //here we do not return a promise, as we dont want more nested forEP
            });
        })
        .then(()=> resolve(namesList));
  });

}

For more examples, take a look at the tests within test folder.