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title: What is __proto__ in JavaScript? | daily.dev
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# What is __proto__ in JavaScript?

**[JavaScript in Plain English](https://daily.dev/sources/jsPlainEnglish)** · 5 min read · 60 upvotes · 5 comments

## Summary

Every single javascript object created, automatically comes with a __proto__ property. By giving assigning a new function sayHi to Object.prototype , every subsequent object that is created will automatically have that function. The usefulness is entirely up to you to decide. But before you go ahead and make use of __ proto__ in your production apps, do note that it has since been deprecated.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://medium.com/javascript-in-plain-english/what-is-proto-b15f16e10b72>

## Community discussion

Top comments from developers on daily.dev.

**@ghost** · 2 upvotes

> Nice explanation of what seems to be "from where did you come proto".

**@lucini** · 1 upvotes

> thanks for the info

**@fahad07khan** · 1 upvotes

> I have read about proto in javaScript, basically, it helps to reuse `custom made` functionality anywhere inside the JS code. pretty helpful!

**@joseyanez** · 0 upvotes

> thanks for the info!!!

**@garvnanwani** · 0 upvotes

> Nicely explained

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---

Tags: [#javascript](https://daily.dev/tags/javascript)

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