---
description: 🚧 施工中
---

# running execution context

[JS](../..) ⟩ [concept](../../../browser/concepts) ⟩ [execution context]() ⟩ running execution context

{% hint style="success" %}
<mark style="color:yellow;">**At any point in time**</mark>, there is <mark style="color:red;">**at most**</mark>**&#x20;**<mark style="color:yellow;">**one**</mark> [](<> "mention") that is actually <mark style="color:yellow;">**executing**</mark> code. This is known as the <mark style="color:purple;">**running execution context**</mark>.

📘 [js-spec](../../../master/ref/js-spec "mention") ⟩ 8.2 [Execution Contexts](https://262.ecma-international.org/6.0/#sec-execution-contexts)
{% endhint %}

{% tabs %}
{% tab title="⭐️ 重點" %}
{% hint style="success" %}
A <mark style="color:yellow;">**stack**</mark> (call stack) is used to <mark style="color:yellow;">**track**</mark> [](<> "mention")(s). The <mark style="color:purple;">**running execution context**</mark> is always the <mark style="color:yellow;">**top**</mark> element of this stack.
{% endhint %}
{% endtab %}

{% tab title="👥 相關" %}
* [lexical-environment](lexical-environment "mention") is <mark style="color:yellow;">**part**</mark> of <mark style="color:purple;">**execution context**</mark>.
{% endtab %}

{% tab title="📗 參考" %}
* [ ] Anil ⟩ [Scope, Lexical Environment and Scope Chain in JavaScript](https://medium.com/@anilakgunes/scope-lexical-environment-and-scope-chain-in-javascript-559aadb7dca8) ⭐️
{% endtab %}

{% tab title="📘 手冊" %}
* [ ] [js-spec](../../../master/ref/js-spec "mention") ⟩&#x20;
  * [ ] [Execution Contexts](https://262.ecma-international.org/6.0/#sec-execution-contexts)
  * [ ] [running execution context](https://tc39.es/ecma262/#running-execution-context)
{% endtab %}

{% tab title="🚧" %}
* [ ] call stack
* [x] running execution context
{% endtab %}
{% endtabs %}
