What's the best way to iterate over JavaScript object properties?

[FlyingLeaf]

I’m working with a JavaScript object that has multiple key-value pairs like this:

var settings = {
    "theme": "dark",
    "language": "english",
    "notifications": "enabled"
};

I need to go through each property in this object and access both the property names and their corresponding values. What are the different methods I can use to iterate through all the properties? I’ve heard about for…in loops but I’m not sure if that’s the only way or the best approach. Are there any modern JavaScript methods that might work better for this kind of task?

[SurfingWave]

The for…in loop is solid for most cases, despite what people say. I’ve used it heavily in production and never had issues with plain objects. Something like for (let prop in settings) { console.log(prop, settings[prop]); } works great. The prototype chain thing only matters with custom prototypes, which is rare in typical web dev. Performance-wise, for…in beats Object.entries() for simple iteration since you’re not creating an extra array. But if you need array methods afterward, Object.entries() makes sense. I stick with for…in for basic iteration and only use Object.entries() when I need those array methods.

[Sky24]

Object.entries() is your best bet here. It gives you an array of key-value pairs that you can loop through with forEach or a regular for loop. Like Object.entries(settings).forEach(([key, value]) => { console.log(key, value); }). Way cleaner than for…in since you don’t have to deal with prototype chain stuff. Object.keys() works too if you just need the property names - then grab values with settings[key]. for…in is fine but it grabs inherited properties, so you might need hasOwnProperty() checks. I’ve been using Object.entries() as my default since ES2017 support got solid.

[Luke_Brilliant]

object.values() is seriously underrated - perfect when you just need the values and don’t care about keys. something like object.values(settings).forEach(val => console.log(val)) and you’re done. pair it with object.keys() if you need them separately. also, if you’re starting from scratch instead of dealing with existing objects, map has built-in iteration with for…of loops which is pretty sweet.