@typed-utils/json
v1.0.1
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Utilities for working with JSON values in a typesafe way
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typed-json-utils
Utilities for working with JSON values in a typesafe way
This package provides facilities for working with JSON values in a typesafe way.
A "JSON value" is a value that could be produced by
JSON.parse
:
- strings
- numbers
- booleans
- null
- objects whose keys are strings and whose values are JSON values
- arrays whose values are JSON values
Table of Contents
Install
$ npm install typed-json-utils
Usage
import { isArray, isObject, isPrimitive } from "typed-json-utils";
console.log(isArray([1, 2, 3])); // true
console.log(isObject({ a: 1, b: 2, c: 3 })); // true
// isObject refers to a *JSON* object, and therefore does not return
// true for arrays.
console.log(isObject([1, 2, 3])); // false
console.log(isPrimitive(3, Number)); // true
console.log(isPrimitive(3, String)); // false
You can use these utilities to narrow down types.
import {
isArray,
isObject,
isPrimitive,
type JsonValue,
} from "typed-json-utils";
export function stringify(value: JsonValue): string {
if (value === null) {
return "null";
}
if (isPrimitive(value)) {
// value is string, number, boolean or undefined
return JSON.stringify(value);
}
if (isArray(value)) {
// value is JsonArray
return `[${value.map(stringify).join(", ")}]`;
}
if (isObject(value)) {
// value is JsonObject
return `{${Object.entries(value)
.map(([key, value]) => {
// key is string, value is JsonValue
return `${key}: ${stringify(value)}`;
})
.join(", ")}}`;
}
// value is never
}
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Contributing
License
MIT © 2023 Yehuda Katz