Basic node interaction: API call Get_node_info()

IOTA101_696A395DC61B.js

// The snippet is a part of the IOTA Developer Essentials project. You can reach it at https://hribek25.github.io/IOTA101/
// Complete description and story behind the snippet is available at: https://hribek25.github.io/IOTA101/Allchapters_javascript.ipynb.html#696A395DC61B
// Requirement: A core module of IOTA Javascript Library (!npm install @iota/core)

var iotalib = require('@iota/core'); // loading iota.js core module. More info: https://github.com/iotaledger/iota.js/tree/next/packages/core

// composerAPI initialization of the iota.js library
var iota = iotalib.composeAPI({
    'provider': 'https://nodes.thetangle.org:443'
});

// basic API call to double check health conditions
var promise = iota.getNodeInfo()
                    .then(info => {
                        console.log(info);
                        // Basic check whether node is in sync or not
                        // Elementary rule is that "latestMilestoneIndex" should equal to "latestSolidSubtangleMilestoneIndex" or be very close
                        if (Math.abs(info['latestMilestoneIndex'] - info['latestSolidSubtangleMilestoneIndex']) > 3) {
                            console.log('\r\nNode is probably not synced!');
                        } else {
                            console.log('\r\nNode is probably synced!');
                        }
                    })
                    .catch(error => {
                        console.log('Request error: ${error.message}')
                    });