Sort JavaScript object by key

Maintaining key-value link when sorting

By leveraging the combined power of Object.keys(), .sort() and .reduce(), we can create a sorted object, with keys in alphabetical order and values intact:

const obj = { lemur: 3, antelope: 1, zebra: 2 };

// 3 animals entered, only 1 can be the first in line 🐾
const sortedObj = Object.keys(obj)
  .sort()
  .reduce((acc, key) => {
    acc[key] = obj[key];
    return acc;
  }, {});

console.log(sortedObj); // {antelope: 1, lemur: 3, zebra: 2}
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Unraveling the mystery of key orders

ES2015 livened up the party and declared how keys should make an entrance when we iterate through our objects:

1. Integer keys (treated as array indices) strut in first.
2. Then, String keys dance through in the order they were created.
3. Finally, Symbol keys make a grand entrance (also in creation order).

But hold your horses! 🐎 This isn’t a universal party — some old environments might not play by the ES2015 rules.

Wrestling with numeric keys

Beware of numeric keys' sly behaviour. They like to be considered as array indices, meaning they'll step ahead of string and symbol keys on the dance floor:

const numericObj = { 10: 'val10', 2: 'val2', 1: 'val1' };

// Numbers kick-start the party! 🥳
const sortedNumericObj = Object.keys(numericObj)
  .sort((a, b) => a - b)
  .reduce((acc, key) => {
    acc[key] = numericObj[key];
    return acc;
  }, {});

console.log(sortedNumericObj); // {1: 'val1', 2: 'val2', 10: 'val10'}


With the .sort() function, we can marshal, maneuver, and maintain control of these unruly numerical strings.

Navigating the choppy waters of edge cases

Sailing smoothly through the sort() seas means squaring off against a few challenging creatures:

• Mixed characters: The Unicode sea monster can cause keys like '10a' to appear before '2a'. Always watch out for mixed-number and string keys.
• Symbol keys: These mythical creatures are elusive and rarely sighted in Object.keys() and Object.entries().

Dodging the backward compatibility bullet with var

If your ship sails on the older, pre-ES6 seas, use var in place of const or let, for bigger fish have been fried with lesser equipment 💥:

var nonES6Sorted = Object.keys(obj).sort().reduce(function (acc, key) {
  acc[key] = obj[key];
  return acc;
}, {});
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Ensuring accurate results (accuracy check)

Remember to cross-check your sorted object with the map (expected results) - easier said than done when wrestling with krakens! 🦑

You might need to customize comparison methods depending on your journey's conditions.

Manipulating object values while sorting

In a twist of plot, suppose you also need to attend to the high seas' values while you're journeying on the keys:

// Beware of the Mutiny on the Bounty! ⚓
const sortByValue = Object.entries(obj)
  .sort((a, b) => a[1] - b[1])
  .reduce((acc, [key, value]) => {
    acc[key] = value;
    return acc;
  }, {});
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Rethinking the in-place algorithms

As it turns out, sorting the keys of an object in-place isn’t always the hero our story needs.

In some instances, just as in every good story, the original order might need to be preserved for a plot twist. Consider the implications of the story context when casting your order-changing spells.

Visualising the sorted objects

Stepping away from the tumultuous programming seas, let's dry off in the library of sorted books:

Before: 📘📗📙📕📚 (Books just wildly thrown on the shelf)

//Giving these books their spots! 🏫
const sortedShelf = Object.keys(unsortedShelf)
    .sort()
    .reduce((obj, key) => { 
        obj[key] = unsortedShelf[key]; 
        return obj;
    }, {});
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After: 📕📗📘📙📚 (Books now quietly resting in alphabetical order)

From unruly chaos, order has been achieved - each book finds its place, much like sorting the keys in our object!

Advanced techniques for swashbuckling through the sort() sea

Stable sorting and custom comparison functions are bold tools you'll need to successfully navigate these unruly seas:

• Stable sorting is a lifesaver in stormy weather. Introduced in ES2019, it maintains identical order while changing everything else.

• Custom comparison functions are like secret maps in a bottle. They can lead to unexpected treasures:

// Pirates love maintaining their own code of conduct! 🏴‍☠️
const caseInsensitiveSort = Object.keys(obj)
  .sort((a, b) => a.toLowerCase().localeCompare(b.toLowerCase()))
  .reduce((acc, key) => {
    acc[key] = obj[key];
    return acc;
  }, {});
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Troubleshooting and confronting common issues

When the ship seems to be sinking, check the object structure, the data types of the keys, and if your crew (environment) can support the methods being used. Any of these could be spotting the holes in your sturdy ship!