<script>
O elemento HTML <script>
é usado para incluir ou referenciar um script executável.
Categorias de conteúdo | Conteúdo de metadados, Fluxo de conteúdo, Conteúdo fraseado. |
---|---|
Conteúdo Permitido | Script dinâmico, como text/javascript . |
Omissão de tag | None, both the starting and ending tag are mandatory. |
Pais permitidos | Qualquer elemento que aceite conteúdo de metadados, ou qualquer elemento que aceite conteúdo fraseado. |
Regras ARIA permitidas | Nenhuma |
Interface DOM | HTMLScriptElement |
Atributos
Esse elemento inclui os atributos globais.
async
HTML5- Um atributo booleano indicando que o navegador deve, se possível, executar o script assíncronamente.
-
Esse atributo não deve ser utilizado se o atributo
src
estiver ausente (ex. scripts embutidos). Se incluído, nesse caso, ele não terá nenhum efeito. -
Scripts inseridos dinamicamente (usando
document.createElement
) são executados assincronamente por padrão, então para turna-lo uma execução síncrona (ex. executar scripts na ordem que eles foram carregados) atribuaasync=false
. - Veja Browser compatibility para notas no suporte do navegador. Veja também Scripts assíncronos para asm.js.
crossorigin
- Elementos
script
passam o mínimo de informação parawindow.onerror
em scripts que não passem na checagem do CORS. Para permitir logs de erro para sites que usem domínimos diferentes para arquivos estáticos, use esse atributo. Veja CORS settings attributes par uma explicação mais detalhada dos argumentos válidos. defer
- Esse atributo Boleano é usado para indicar ao navegador que o script deve ser executado depois que o documento tenha sido parseado, mas antes de disparar o evento
DOMContentLoaded
- Scripts com o atributo
defer
vão impedir que o evento DOMContentLoaded seja disparado até que o script seja carregado e tenha terminado de ser avaliado. -
Esse atributo não deve ser usado se o atibuto
src
estiver ausente (ex. scripts inline), nesse caso ele não vai ter efeito. -
Para conseguir um efeito similar para scripts inseridos dinamicamente use
async=false
. Scripts com o atributodefer
vão ser executados na ordem em que aparecem nodocument
. integrity
- Contains inline metadata that a user agent can use to verify that a fetched resource has been delivered free of unexpected manipulation. See Subresource Integrity.
nomodule
- This Boolean attribute is set to indicate that the script should not be executed in browsers that support ES6 modules — in effect, this can be used to serve fallback scripts to older browsers that do not support modular JavaScript code.
src
- This attribute specifies the URI of an external script; this can be used as an alternative to embedding a script directly within a document. If a
script
element has asrc
attribute specified, it should not have a script embedded inside its tags. text
- Like the
textContent
attribute, this attribute sets the text content of the element. Unlike thetextContent
attribute, however, this attribute is evaluated as executable code after the node is inserted into the DOM. type
-
Indicates the type of script represented. The value of this attribute will be in one of the following categories:
- Omitted or a JavaScript MIME type: For HTML5-complient browsers this indicates the script is JavaScript. HTML5 spec urges authors to omit the attribute rather than provided a redundant MIME type. In earlier browsers, this identified the scripting language of the embedded or imported (via the
src
attribute) code. JavaScript MIME types are listed in the specification. module
: HTML5 For HTML5-complient browsers the code is treated as a JavaScript module. Processing of the script contents are not affected by thecharset
anddefer
attributes. For information on usingmodule
, see ES6 in Depth: Modules.- Any other value or MIME type: Embedded content is treated as a data block which won't be processed by the browser. The
src
attribute will be ignored.
Note that in Firefox you can use advanced features such as let statements and other features in later JS versions, by using
type=application/javascript;version=1.8
. Beware, however, that as this is a non-standard feature, this will most likely break support for other browsers, in particular Chromium-based browsers.For how to include exotic programming languages, read about Rosetta.
- Omitted or a JavaScript MIME type: For HTML5-complient browsers this indicates the script is JavaScript. HTML5 spec urges authors to omit the attribute rather than provided a redundant MIME type. In earlier browsers, this identified the scripting language of the embedded or imported (via the
-
Atributos obsoletos
charset
- If present, its value must be an ASCII case-insensitive match for "
utf-8
". Both it’s unnecessary to specify thecharset
attribute, because documents must use UTF-8, and thescript
element inherits its character encoding from the document. language
- Like the
type
attribute, this attribute identifies the scripting language in use. Unlike thetype
attribute, however, this attribute’s possible values were never standardized. Thetype
attribute should be used instead.
Notas
Scripts without async
or defer
attributes, as well as inline scripts, are fetched and executed immediately, before the browser continues to parse the page.
The script should be served with the text/javascript
MIME type, but browsers are lenient and only block them if the script is served with an image type (image/*
), a video type (video/*
), an audio (audio/*
) type, or text/csv
. If the script is blocked, an error
is sent to the element, if not a success
event is sent.
Exemplos
<!-- HTML4 and (x)HTML -->
<script type="text/javascript" src="javascript.js"></script>
<!-- HTML5 -->
<script src="javascript.js"></script>
Specifications
Specification | Status | Comments |
---|---|---|
HTML Living Standard The definition of '<script>' in that specification. |
Padrão em tempo real | Adds the module type |
HTML5 The definition of '<script>' in that specification. |
Recomendação | |
HTML 4.01 Specification The definition of '<script>' in that specification. |
Recomendação | |
Subresource Integrity The definition of '<script>' in that specification. |
Recomendação | Adds the integrity attribute. |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 1.0 | (Yes) | 1.0 (1.7 or earlier)[2] | (Yes) | (Yes) | (Yes) |
async attribute | (Yes)[1] | (Yes) | 3.6 (1.9.2)[1] | 10[1] | 15[1] | (Yes)[1] |
defer attribute | (Yes) | (Yes) | 3.5 (1.9.1)[6] |
4[3] |
Não suportado | (Yes) |
crossorigin attribute | 30.0 | (Yes) | 13 (13) | Não suportado | 12.50 | (Yes)[4] |
integrity attribute | 45.0 | Não suportado | 43 (43) | Não suportado[5] |
Feature | Android | Android Webview | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | 1.0 (1.0)[2] | (Yes) | (Yes) | (Yes) | (Yes) |
async attribute | (Yes)[1] | (Yes)[1] | (Yes) | 1.0 (1.0)[1] | Não suportado[1] | ?[1] | (Yes)[1] | (Yes)[1] |
defer attribute | (Yes) | (Yes) | (Yes) | 1.0 (1.0) | Não suportado | ? | (Yes) | (Yes) |
integrity attribute | Não suportado | 45.0 | Não suportado | 43 (43) | 45.0 |
[1] In older browsers that don't support the async
attribute, parser-inserted scripts block the parser; script-inserted scripts execute asynchronously in IE and WebKit, but synchronously in Opera and pre-4.0 Firefox. In Firefox 4.0, the async
DOM property defaults to true
for script-created scripts, so the default behavior matches the behavior of IE and WebKit. To request script-inserted external scripts be executed in the insertion order in browsers where the document.createElement("script").async
evaluates to true
(such as Firefox 4.0), set .async=false
on the scripts you want to maintain order. Never call document.write()
from an async
script. In Gecko 1.9.2, calling document.write()
has an unpredictable effect. In Gecko 2.0, calling document.write()
from an async
script has no effect (other than printing a warning to the error console).
[2] Starting in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1), inserting script elements that have been created by calling document.createElement("script")
into the DOM no longer enforces execution in insertion order. This change lets Gecko properly abide by the HTML5 specification. To make script-inserted external scripts execute in their insertion order, set .async=false
on them.
Also, <script>
elements inside <iframe>
, <noembed>
and <noframes>
elements are now executed, for the same reasons.
[3] In versions prior to Internet Explorer 10 Trident implemented <script>
by a proprietary specification. Since version 10 it conforms to the W3C specification.
[4] The crossorigin
attribute was implemented in WebKit in WebKit bug 81438.
[5] WebKit bug 148363 tracks WebKit implementation of Subresource Integrity (which includes the integrity
attribute).
[6] Desde Gecko 1.9.2 (Firefox 3.6 / Thunderbird 3.1 / Fennec 1.0), o atributo defer
is ignorado nos scripts que nao tenham o atributo src
. However, in Gecko 1.9.1 (Firefox 3.5 / Thunderbird 3.0 / SeaMonkey 2.0) even inline scripts are deferred if the defer
attribute is set.