jsPrepend

Inserts the specified content before the existing response body. (This only works for responses with content-type containing javascript and a status code containing a body (e.g., 200/500).)

⚠️ Note: Requests without a body, such as 204 and 304 responses, are not affected.

Rule Syntax

txt

pattern jsPrepend://value [filters...]

Parameters	Description	Detailed Documentation
pattern	An expression to match against the request URL	Match Pattern Documentation
value	Text or binary content. Supports the following types: • Directory/File Path • Remote URL • Inline/Embedded/Values Content	Operation Instruction Documentation
filters	Optional filters. Supports matching: • Request URL/Method/Headers/Content • Response Status Code/Headers	Filter Documentation

Configuration Example

Inline Method

txt

www.example.com/path1 jsPrepend://(Hello) file://(-test-)
www.example.com/path2 jsPrepend://(Hello) file://(-test-) resType://js
www.example.com/path3 jsPrepend://(Hello) file://(-test-) resType://css

Request https://www.example.com/path1/to. The response content becomes
html
```
<!DOCTYPE html>
<script>Hello</script>-test-
```
Request https://www.example.com/path2/to. The response content becomes Hello-test-
Request The response content of https://www.example.com/path3/to becomes -test-

Embedded/Values Method

txt

``` body.txt
Hello world.
```
www.example.com/path1 jsPrepend://{body.txt} file://(-test-)
www.example.com/path2 jsPrepend://{body.txt} file://(-test-) resType://js
www.example.com/path3 jsPrepend://{body.txt} file://(-test-) resType://css

Requesting https://www.example.com/path1/to, the response content becomes
html
```
<!DOCTYPE html>
<script>Hello world.</script> -test-
```
Requesting https://www.example.com/path2/to, the response content becomes Hello world.-test-
Request https://www.example.com/path3/to. The response content becomes -test-.

Local/Remote Resources

txt

www.example.com/path1 jsPrepend:///User/xxx/test.js
www.example.com/path2 jsPrepend://https://www.xxx.com/xxx/params.js
# Editing a temporary file
www.example.com/path3 jsPrepend://temp/blank.js

Set `<script>` Tag Attributes for Injected Scripts

Scripts injected into HTML pages via jsPrepend are automatically wrapped in <script> tags by Whistle. To set additional attributes for these tags—such as nomodule, module, defer, async, or crossorigin—you can use the lineProps parameter for configuration.

txt

www.example.com/path1 jsPrepend://https://www.xxx.com/xxx/params.js lineProps://nomodule
www.example.com/path2 jsPrepend://https://www.xxx.com/xxx/params.js lineProps://module
www.example.com/path3 jsPrepend://https://www.xxx.com/xxx/params.js lineProps://defer
www.example.com/path4 jsPrepend://https://www.xxx.com/xxx/params.js lineProps://async
www.example.com/path5 jsPrepend://https://www.xxx.com/xxx/params.js lineProps://crossorigin

Attribute Descriptions and Examples

Attribute	Purpose	Configuration Example
`nomodule`	Executes in traditional browsers; this script will run in browsers that do not support ES modules.	`lineProps://nomodule`
`module`	Declares the script as an ES module, enabling modular imports.	`lineProps://module`
`defer`	Loads asynchronously and executes after the document has been parsed.	`lineProps://defer`
`async`	Loads asynchronously and executes immediately after download.	`lineProps://async`
`crossorigin`	Enables Cross-Origin Resource Sharing (CORS) mode.	`lineProps://crossorigin`

Inject content before the response content (Prepend To Body): resPrepend
Inject HTML content before the response content (Prepend HTML To Body, response type must be text/html): htmlPrepend
Inject CSS content before the response content (Prepend CSS To Body, response type must be text/html or text/css): cssPrepend
Inject JS content before the response content (Prepend JS To Body, response type must be text/html, text/css, or application/javascript): jsPrepend
Replace the response content (Replace Body): resBody
Replace the response content with HTML content (Replace Body, response type must be text/html): htmlBody
Replace the response content with CSS content (Replace Body, response type must be text/html or text/css): cssBody
Replace the response content with JS content (Replace Body, response type must be text/html, text/css, or application/javascript): jsBody
Append content after the response content (Append To Body): resAppend
Append HTML content after the response content (Append HTML To Body, response type must be text/html): htmlAppend
Append CSS content after the response content (Append CSS To Body, response type must be text/html or text/css): cssAppend
Append JS content after the response content (Append JS To Body, response type must be text/html, text/css, or application/javascript): jsAppend
Replace the response content using keywords or regular expressions (Modify Body Text): resReplace
Override JSON/Form objects in the response content (Modify Form/JSON): resMerge
Delete a property from a JSON/Form object in the response content (Delete Form/JSON): delete://resBody.xxx

jsPrepend ​

Rule Syntax ​

Configuration Example ​

Inline Method ​

Embedded/Values Method ​

Local/Remote Resources ​

Set <script> Tag Attributes for Injected Scripts ​

Attribute Descriptions and Examples ​

Associated Protocols ​