d3.js v5 - Promise.all replaced d3.queue

Question

I've been using d3.js v4 for sometime now and I've learned that Mike Bostock has replaced the d3.queue in the v5 release with the Promise native JavaScript object. I would like to check with you if this code that I have written is properly queuing (asynchronously) these URL's:

var makeRequest = function() {
    "use strict";

    var bli = [
        "http://stats.oecd.org/sdmx-json/data/BLI2013/all/all",
        "http://stats.oecd.org/sdmx-json/data/BLI2014/all/all",
        "http://stats.oecd.org/sdmx-json/data/BLI2015/all/all",
        "http://stats.oecd.org/sdmx-json/data/BLI2016/all/all",
        "http://stats.oecd.org/sdmx-json/data/BLI/all/all"
    ];

    var promises = [];

    bli.forEach(function(url) {
        promises.push(
            new Promise(function(resolve, reject) {
                d3
                    .json(url)
                    .then(function(response) {
                        resolve(response);
                    })
                    .catch(function(error) {
                        console.log("Error on: " + url + ". Error: " + error);
                        reject(error);
                    });
            })
        );
    });

    Promise.all(promises).then(function(values) {
        console.log(values);
    });
};

makeRequest();

The code seems to function properly, but, is this proper code or is there a better way (a best practice approach) for queuing with Promise.all and d3.js? Is the catch error properly implemented?

Answer 1

You can simplify that code a lot: you don't net to use new Promise with d3.json, since d3.json will itself create the promise.

So, you can just do:

var files = ["data1.json", "data2.json", "data3.json"];
var promises = [];

files.forEach(function(url) {
    promises.push(d3.json(url))
});

Promise.all(promises).then(function(values) {
    console.log(values)
});

Or, if you're into the code golf, even shorter:

var files = ["data1.json", "data2.json", "data3.json"];

Promise.all(files.map(url => d3.json(url))).then(function(values) {
    console.log(values)
});

Since I cannot use JSON files in the S.O. snippet, check the console in this bl.ocks: https://bl.ocks.org/GerardoFurtado/f08993c9c729b0b3452ef1803ad9dcbf/c4b45c5acce6033085a667cbb7d34203d15de0f0