json-override

The json-override snippet wraps JSON.parse to override values from the same list as override-property-read.

It wraps both JSON.parse and Response.prototype.json, so a payload is covered whether the page parses it itself or reads it straight off a fetch response with await response.json().

Parameters

Name	Description	Mandatory
`rawOverridePaths`	Space-separated properties to override. Accepts property chains (`foo.bar`), `{}` for objects, `[]` for arrays. Each entry can also be a `jsonpath(...)` query — see below. The `{-}` and `[-]` removal placeholders accepted by `json-prune` are not supported here, since removing the containing element has no meaning for an override.	Yes
`value`	The value to override the property with.	Yes
`rawNeedlePaths`	Space-separated properties — all must be present for override to occur.	No
`filter`	String or regex to look for in the raw string before JSON.parse. If no match, no further search is done.	No

Possible override values

Value	Definition
`undefined`
`false`	The boolean, not the string
`true`	The boolean, not the string
`falseStr`	`"false"` as a string
`trueStr`	`"true"` as a string
`null`
`''`	Empty string
`decimal integer`	The number
`noopFunc`	Function with empty body
`trueFunc`	Function returning true
`falseFunc`	Function returning false
`emptyArray`	Array with no elements
`emptyObj`	Object with no properties

JSONPath mode

When an entry in rawOverridePaths starts with jsonpath(, the query is evaluated against the parsed object and every property it matches is overridden with value, interpreted through the vocabulary above. Use it when the placeholder syntax cannot express the shape you need — for example filtering on a sibling property's value, or matching at an unknown depth with $...

rawOverridePaths is split on spaces, so a query must not contain spaces.
Quotes inside a filter expression must be written \', or the parser strips them.
Entries are evaluated independently, so plain properties and queries can be mixed in one filter.
For the supported query syntax, see JSONPath evaluator. For the escaping rules, see Snippets Overview.

Filter examples

Filter	Result
`json-override ghl_label ''`	Replaces `ghl_label` with empty string from every object parsed with `JSON.parse`.
`json-override 'children text' ''`	Replaces all `children` and `text` properties with empty string.
`json-override ghl_label '' text`	Replaces `ghl_label` from every object that has a `text` property.
`json-override data.nested.[].ad ''`	Replaces all `ad` values listed inside an array with empty string.
`json-override data.nested.{}.ad ''`	Replaces `ad` values from any nested object properties.
`json-override 'jsonpath($..ads.enabled)' false`	JSONPath mode. Sets every `ads.enabled` property at any depth to the boolean `false`.
`json-override 'jsonpath($.items[?(@.type==\'ad\')].visible)' false`	Sets `visible` to `false` only on the `items` elements whose `type` is `ad` — a condition on the data that the placeholder syntax cannot express.

Debugging

Message	When	Definition
`Wrapped JSON.parse for override`	After wrapping	The API was wrapped.
`Wrapped Response.json for override`	After wrapping	Payloads read via `await response.json()` are covered too.
`Iterating over array at []` or `Iterating over object at {}`	Parsing placeholder	The path leading to the placeholder is accurate.
`Found <<rawOverridePath>> replaced it with <<value>>`	After override	A property was found and overridden.
`Invalid JSONPath query: <<path>>. Error: <<message>>`	Right after the snippet fires	The query could not be compiled, so that entry will never match.
`JSONPath match found at [<<key>>], replaced with <<value>>`	Per matched property	A property matched the query and was overridden. One message per match.
`JSONPath evaluation failed for: <<path>>. Error: <<message>>`	Evaluating a compiled query threw	That object is left untouched.