Enumerating JavaScript Objects: Understanding the for in Loop

In this tutorial we take a look at the features of the for in loop and how to use it to iterate over the properties of a JavaScript Object.

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[nageshthotakura]

A Great Javascript Channel. Thank you for your efforts. May God Bless You.

[amguruprasath]

simple beautiful and in-depth. You're doing a great service thank you!

[salimahusain]

I had an object with 218 attributes that i set and I wanted to loop through all of them and I thought I would have to *make* an array of all the attribute names. You saved me so much time. Thank you.

[heathergarcia]

Thank you so much for this video! I was stuck on some "for in loop" challenge questions @ school and this video helped me solve the questions.

[shabnamnaaz]

your videos are really unique, thankyou steven :) .

[nwobodogeorge]

Thank you for the teaching. I learnt a lot from it.

[batchrocketproject]

I experimented with adding named properties to array objects and they are enumerated with the for-in loop. The inbuilt .length property is not (and returns false). I attempted to set the .length property's enumerable attribute to true (using ar.length.enumerable = true;). When I checked its enumerability with ar.propertyIsEnumerable("length"), the return value is true. However, when I repeated the for-in loop on the array, the length property was ignored. I remain confused by this and would appreciate any insight.