getPathValue() function for deep objects

Question

This is a follow-up question to this: getPathValue() function for deep objects with arrays and with packed JSON

The accepted answer works very well in most situations:

Answer 1

Change:

.split('.')

By:

.split('.').filter(Boolean)

It will remedy a dot that got placed at the very beginning of the string, which is what happens when the input starts with a [, like in [0].

Demo:

function getPathValue(object, path) {
    return path
       .replace(/\[/g, '.')
       .replace(/\]/g, '')
       .split('.').filter(Boolean)
       .reduce(function (o, k) {
           return (typeof o === 'string' ? JSON.parse(o) : (o || {}))[k];
       }, object);
}

var obj = [{"currencyPair":"EUR/USD","timestamp":"1546028298698","bidBig":"1.14","bidPips":"450","offerBig":"1.14","offerPips":"457","high":"1.14253","low":"1.14732","open":"1.14305"},{"currencyPair":"USD/JPY","timestamp":"1546028299095","bidBig":"110.","bidPips":"326","offerBig":"110.","offerPips":"336","high":"110.222","low":"111.062","open":"111.012"}];

value = getPathValue(obj, '[0].bidPips');

console.log(value);

It can be done easier though, by replacing the replace and split calls by one match call:

function getPathValue(object, path) {
    return path
       .match(/[^[\].]+/g)
       .reduce(function (o, k) {
           return (typeof o === 'string' ? JSON.parse(o) : (o || {}))[k];
       }, object);
}

var obj = [{"currencyPair":"EUR/USD","timestamp":"1546028298698","bidBig":"1.14","bidPips":"450","offerBig":"1.14","offerPips":"457","high":"1.14253","low":"1.14732","open":"1.14305"},{"currencyPair":"USD/JPY","timestamp":"1546028299095","bidBig":"110.","bidPips":"326","offerBig":"110.","offerPips":"336","high":"110.222","low":"111.062","open":"111.012"}];
value = getPathValue(obj, '[0].bidPips');

console.log(value);

Answer 2

You could remove a leading dot before splitting.

function getValue(object, path) {
    return path
       .replace(/\[/g, '.')
       .replace(/\]/g, '')
       .replace(/^\./, '')
       .split('.')
       .reduce(function (o, k) {
           return (typeof o === 'string' ? JSON.parse(o) : (o || {}))[k];
       }, object);
}

var obj = [{"currencyPair":"EUR/USD","timestamp":"1546028298698","bidBig":"1.14","bidPips":"450","offerBig":"1.14","offerPips":"457","high":"1.14253","low":"1.14732","open":"1.14305"},{"currencyPair":"USD/JPY","timestamp":"1546028299095","bidBig":"110.","bidPips":"326","offerBig":"110.","offerPips":"336","high":"110.222","low":"111.062","open":"111.012"},{"currencyPair":"GBP/USD","timestamp":"1546028246468","bidBig":"1.26","bidPips":"974","offerBig":"1.26","offerPips":"988","high":"1.26350","low":"1.27087","open":"1.26505"},{"currencyPair":"EUR/GBP","timestamp":"1546028296658","bidBig":"0.90","bidPips":"127","offerBig":"0.90","offerPips":"140","high":"0.90034","low":"0.90601","open":"0.90355"},{"currencyPair":"USD/CHF","timestamp":"1546028296551","bidBig":"0.98","bidPips":"470","offerBig":"0.98","offerPips":"481","high":"0.97896","low":"0.99113","open":"0.98854"},{"currencyPair":"EUR/JPY","timestamp":"1546028299289","bidBig":"126.","bidPips":"322","offerBig":"126.","offerPips":"336","high":"126.256","low":"127.204","open":"127.008"},{"currencyPair":"EUR/CHF","timestamp":"1546028296543","bidBig":"1.12","bidPips":"714","offerBig":"1.12","offerPips":"726","high":"1.12146","low":"1.13180","open":"1.12920"},{"currencyPair":"USD/CAD","timestamp":"1546028299908","bidBig":"1.36","bidPips":"470","offerBig":"1.36","offerPips":"485","high":"1.35946","low":"1.36613","open":"1.36142"},{"currencyPair":"AUD/USD","timestamp":"1546028296222","bidBig":"0.70","bidPips":"445","offerBig":"0.70","offerPips":"453","high":"0.70238","low":"0.70695","open":"0.70288"},{"currencyPair":"GBP/JPY","timestamp":"1546028297767","bidBig":"140.","bidPips":"123","offerBig":"140.","offerPips":"148","high":"139.495","low":"140.628","open":"140.462"}],
    value = getValue(obj, '[0]');
    
console.log(value)