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Traverse JSON Schema passing each schema object to callback

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npm install json-schema-traverse


const traverse = require('json-schema-traverse');
const schema = {
  properties: {
    foo: {type: 'string'},
    bar: {type: 'integer'}

traverse(schema, {cb});
// cb is called 3 times with:
// 1. root schema
// 2. {type: 'string'}
// 3. {type: 'integer'}

// Or:

traverse(schema, {cb: {pre, post}});
// pre is called 3 times with:
// 1. root schema
// 2. {type: 'string'}
// 3. {type: 'integer'}
// post is called 3 times with:
// 1. {type: 'string'}
// 2. {type: 'integer'}
// 3. root schema

Callback function cb is called for each schema object (not including draft-06 boolean schemas), including the root schema, in pre-order traversal. Schema references ($ref) are not resolved, they are passed as is. Alternatively, you can pass a {pre, post} object as cb, and then pre will be called before traversing child elements, and post will be called after all child elements have been traversed.

Callback is passed these parameters:

  • schema: the current schema object
  • JSON pointer: from the root schema to the current schema object
  • root schema: the schema passed to traverse object
  • parent JSON pointer: from the root schema to the parent schema object (see below)
  • parent keyword: the keyword inside which this schema appears (e.g. properties, anyOf, etc.)
  • parent schema: not necessarily parent object/array; in the example above the parent schema for {type: 'string'} is the root schema
  • index/property: index or property name in the array/object containing multiple schemas; in the example above for {type: 'string'} the property name is 'foo'

Traverse objects in all unknown keywords

const traverse = require('json-schema-traverse');
const schema = {
  mySchema: {
    minimum: 1,
    maximum: 2

traverse(schema, {allKeys: true, cb});
// cb is called 2 times with:
// 1. root schema
// 2. mySchema

Without option allKeys: true callback will be called only with root schema.

Enterprise support

json-schema-traverse package is a part of Tidelift enterprise subscription - it provides a centralised commercial support to open-source software users, in addition to the support provided by software maintainers.

Security contact

To report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure. Please do NOT report security vulnerability via GitHub issues.



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