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type
Runtime validation and processing of JavaScript types
- Respects language nature and acknowledges its quirks
- Allows coercion in restricted forms (rejects clearly invalid input, normalizes permissible type deviations)
- No transpilation implied, written to work in all ECMAScript 3+ engines
Use case
Validate arguments input in public API endpoints.
For validation of more sophisticated input structures (as deeply nested configuration objects) it's recommended to consider more powerful schema based utlities (as AJV or @hapi/joi)
Example usage
Bulletproof input arguments normalization and validation:
const ensureString = require('type/string/ensure')
, ensureDate = require('type/date/ensure')
, ensureNaturalNumber = require('type/natural-number/ensure')
, isObject = require('type/object/is');
module.exports = (path, options = { min: 0 }) {
path = ensureString(path, { errorMessage: "%v is not a path" });
if (!isObject(options)) options = {};
const min = ensureNaturalNumber(options.min, { default: 0 })
, max = ensureNaturalNumber(options.max, { isOptional: true })
, startTime = ensureDate(options.startTime, { isOptional: true });
};
Installation
npm install type
Utilities
Aside of general ensure
validation util, following kind of utilities for recognized JavaScript types are provided:
*/coerce
Restricted coercion into primitive type. Returns coerced value or null
if value is not coercible per rules.
*/is
Object type/kind confirmation, returns either true
or false
.
*/ensure
Value validation. Returns input value (in primitive cases possibly coerced) or if value doesn't meet the constraints throws TypeError
.
Each */ensure
utility, accepts following options (eventually passed with second argument):
isOptional
- Makes null
or undefined
accepted as valid value. In such case instead of TypeError
being thrown, null
is returned.default
- A value to be returned if null
or undefined
is passed as an input value.errorMessage
- Custom error message. Following placeholders can be used:
%v
- To be replaced with short string representation of invalid value%n
- To be replaced with meaninfgul name (to be passed with name
option) of validated value. Not effective if name
option is not present
errorCode
- Eventual error code to be exposed on .code
error propertyname
- Meaningful name for validated value, to be used in error message, assuming it contains %n
placeholderError
- Alternative error constructor to be used (defaults to TypeError
)
Index
General utils:
Type specific utils:
- Value
- Object
- String
- Number
- BigInt
- Array Like
- Iterable
- Set
- Map
- Date
- Function
- Reg Exp
- Thenable
- Error
- Prototype
Tests
$ npm test