Loop through properties in JavaScript object with Lodash

Use _.forOwn().

_.forOwn(obj, function(value, key) { } );

https://lodash.com/docs#forOwn

Note that forOwn checks hasOwnProperty, as you usually need to do when looping over an object's properties. forIn does not do this check.

Yes you can and lodash is not needed... i.e.

for (var key in myObject.options) {
  // check also if property is not inherited from prototype
  if (myObject.options.hasOwnProperty(key)) { 
    var value = myObject.options[key];
  }
}

Edit: the accepted answer (_.forOwn()) should be https://stackoverflow.com/a/21311045/528262

For your stated desire to "check if a property exists" you can directly use Lo-Dash's has.

var exists = _.has(myObject, propertyNameToCheck);

You can definitely do this with vanilla JS like stecb has shown, but I think each is the best answer to the core question concerning how to do it with lodash.

_.each( myObject.options, ( val, key ) => { 
    console.log( key, val ); 
} );

Like JohnnyHK mentioned, there is also the has method which would be helpful for the use case, but from what is originally stated set may be more useful. Let's say you wanted to add something to this object dynamically as you've mentioned:

let dynamicKey = 'someCrazyProperty';
let dynamicValue = 'someCrazyValue';

_.set( myObject.options, dynamicKey, dynamicValue );

That's how I'd do it, based on the original description.

Lets take below object as example

let obj = { property1: 'value 1', property2: 'value 2'};

First fetch all the key in the obj

let keys = Object.keys(obj) //it will return array of keys

and then loop through it

keys.forEach(key => //your way)

just putting all together

Object.keys(obj).forEach(key=>{/*code here*/})

Loop through properties in JavaScript object with Lodash

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