Truncate a JSON string.

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Examples

``js
import truncateJson from 'truncate-json'

// Object properties and array items beyond maxSize are omitted.
const maxSize = 15
const jsonString = JSON.stringify({ a: 'one', b: 'two' })
console.log(jsonString)
// '{"a":"one","b":"two"}' (21 bytes)
console.log(truncateJson(jsonString, maxSize).jsonString)
// '{"a":"one"}' (11 bytes)
`

`js
// Works deeply inside objects and arrays
const jsonString = JSON.stringify([
'one',
{ a: 'two', b: { c: 'three', d: 'four' } },
'five',
])
console.log(jsonString)
// '["one",{"a":"two","b":{"c":"three","d":"four"}},"five"]' (55 bytes)
const returnValue = truncateJson(jsonString, 40)
console.log(returnValue.jsonString)
// '["one",{"a":"two","b":{"c":"three"}}]' (37 bytes)

// Omitted/truncated properties are returned
console.log(returnValue.truncatedProps)
// [
// { path: [ 1, 'b', 'd' ], value: 'four' },
// { path: [ 2 ], value: 'five' }
// ]
const isTruncated = returnValue.truncatedProps.length !== 0
console.log(isTruncated) // true
`

`js
// Indentation is automatically detected and preserved
const jsonString = JSON.stringify({ a: 'one', b: 'two' }, undefined, 2)
console.log(jsonString)
// '{
// "a": "one",
// "b": "two"
// }' (30 bytes)
console.log(truncateJson(jsonString, 25).jsonString)
// '{
// "a": "one"
// }' (16 bytes)
`

`js
// The top-level value can be any JSON type, not only objects or arrays
const jsonString = JSON.stringify('This is an example top-level string')
console.log(truncateJson(jsonString, 25).jsonString)
// '"This is an example t..."' (25 bytes)
`

Install

`bash
npm install truncate-json
`

This package works in both Node.js >=14.18.0 and
browsers.

This is an ES module. It must be loaded using
an import or import() statement,
not require(). If TypeScript is used, it must be configured to
output ES modules,
not CommonJS.

API

truncateJson(jsonString, maxSize)

jsonString string\
maxSize number\
_Return value_: object

Truncates a JSON string to maxSize bytes.

Any object property or array item beyond the maxSize limit is completely
omitted. Strings are not truncated, except when at the top-level.

$3

The return value is an object with the following properties.

#### jsonString

_Type_: string

jsonString after truncation has been applied.

#### truncatedProps

_Type_: object[]

List of properties having been truncated/omitted.

##### truncatedProps[*].path

_Type_: Array

Property path. This is an array of property keys and/or array indices.

##### truncatedProps[*].value

_Type_: JsonValue

Property value.

Related projects

- is-json-value: Check if a value
is valid JSON
- safe-json-value: ⛑️ JSON
serialization should never fail
- guess-json-indent: Guess the
indentation of a JSON string
- string-byte-length: Get the
UTF-8 byte length of a string
- string-byte-slice: Like
string.slice() but bytewise

Support

For any question, _don't hesitate_ to submit an issue on GitHub.

Everyone is welcome regardless of personal background. We enforce a
Code of conduct in order to promote a positive and
inclusive environment.

Contributing

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sharing it online.

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