Loop through properties in JavaScript object with Lodash

Question

Is it possible to loop through the properties in a JavaScript object  For instance  I have a JavaScript object defined as this   myObject options       property1   value 1     property2   value 2       Properties will get dynamically added to this object  Is there a way for me to just loop through and do a check if a property exists  If so  how

User · Answer

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.

User · Answer

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

User · Answer

In ES6  it is also possible to iterate over the values of an object using the for  of loop  This doesn t work right out of the box for JavaScript objects  however  as you must define an   iterator property on the object  This works as follows    The for  of loop asks the  object to be iterated over   let s call it obj1 for an iterator object  The loop iterates over obj1 by successively calling the next   method on the provided iterator object and using the returned value as the value for each iteration of the loop  The iterator object is obtained by invoking the function defined in the   iterator property  or Symbol iterator property  of obj1  This is the function you must define yourself  and it should return an iterator object   Here is an example   const obj1       a  5    b   hello      Symbol iterator   function         const thisObj   this      let index   0      return         next             let keys   Object keys thisObj           return             value  thisObj keys index                done   index  gt  keys length                                     Now we can use the for  of loop   for  val of obj1      console log val           5 hello

User · Answer

It would be helpful to understand why you need to do this with lodash  If you just want to check if a key exists in an object  you don t need lodash   myObject options hasOwnProperty  property      If your looking to see if a value exists  you can use   invert    invert myObject options  value

User · Answer

For your stated desire to  check if a property exists  you can directly use Lo-Dash s has   var exists     has myObject  propertyNameToCheck

User · Answer

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

User · Answer

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   gt    your way    just putting all together  Object keys obj  forEach key  gt    code here

[javascript] Loop through properties in JavaScript object with Lodash

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