---
description: JS engine used in Chrome/Node.
---

# v8

[JS](../../..) ⟩ [concepts](../../../../browser/concepts) ⟩ [environment](..) ⟩ [JS engine]() ⟩ <mark style="color:purple;">**v8**</mark>

{% hint style="success" %}
a [](<> "mention") used in <mark style="color:yellow;">**Chrome**</mark> / <mark style="color:yellow;">**Edge**</mark> / Opera / [node.js](../node.js "mention").
{% endhint %}

{% tabs %}
{% tab title="⭐️ 重點" %}
{% hint style="warning" %}
<mark style="color:purple;">**v8**</mark> behaves <mark style="color:red;">**contrary**</mark> to the <mark style="color:yellow;">**spec**</mark> in [function-in-block-fib](../../../val/func/declare/function-in-block-fib "mention"):exclamation:
{% endhint %}

{% hint style="danger" %}
<mark style="color:purple;">**v8**</mark> will do [optimize](../../execution-context/lexical-environment/optimize "mention"), be aware:exclamation:
{% endhint %}
{% endtab %}
{% endtabs %}
