@xylabs/assert
Advanced tools
Base functionality used throughout XY Labs TypeScript/JavaScript libraries
@xylabs/assert
Implementation of assertDefinedEx that handles all overloads.
function assertDefinedEx<T>(expr, messageFunc?): T;
Asserts that a value is defined (not undefined) and returns the value. Throws an error if the value is undefined.
T
The type of value to check
Expression to be evaluated for being defined
undefined | T
AssertExMessageFunc<T>
Function that returns a message for the error if expression is undefined
T
The value of the expression (guaranteed to be defined)
Error with the message returned by messageFunc
// Simple usage with a message function
const value = assertDefinedEx(possiblyUndefined, () => 'Value must be defined')
// Using with type narrowing
const config: Config | undefined = loadConfig()
const safeConfig = assertDefinedEx(config, () => 'Config failed to load')
// safeConfig is now type Config (not Config | undefined)
function assertDefinedEx<T, R>(expr, errorFunc?): T;
Asserts that a value is defined (not undefined) and returns the value. Throws a custom error if the value is undefined.
T
The type of value to check
R extends Error
The type of error to throw
Expression to be evaluated for being defined
undefined | T
AssertExErrorFunc<T, R>
Function that returns a custom error instance if expression is undefined
T
The value of the expression (guaranteed to be defined)
Custom error returned by errorFunc
// Using with a custom error
const user = assertDefinedEx(getUser(), () => new UserNotFoundError('User not found'))
function assertDefinedEx<T>(expr): T;
Asserts that a value is defined (not undefined) and returns the value. Throws an error if the value is undefined.
T
The type of value to check
Expression to be evaluated for being defined
undefined | T
T
The value of the expression (guaranteed to be defined)
Use overload with message function instead - passing a message will soon be required
Error with a generic message
function assertDefinedEx<T>(expr, message?): T;
Asserts that a value is defined (not undefined) and returns the value. Throws an error with the provided message if the value is undefined.
T
The type of value to check
Expression to be evaluated for being defined
undefined | T
string
Error message if expression is undefined
T
The value of the expression (guaranteed to be defined)
Replace string with () => string for consistency
Error with the provided message
Implementation of assertEx that handles all overloads.
function assertEx<T>(expr, messageFunc?): T;
Asserts that an expression is truthy and returns the value. Throws an error if the expression is falsy.
T
The type of value to check
Expression to be evaluated for truthiness
undefined | null | T
AssertExMessageFunc<T>
Function that returns a message for the error if expression is falsy
T
The value of the expression (guaranteed to be truthy)
Error with the message returned by messageFunc
// Simple usage with a message function
const value = assertEx(possiblyFalsy, () => 'Value must be truthy')
// Using with type narrowing
const config: Config | null = loadConfig()
const safeConfig = assertEx(config, () => 'Config failed to load')
// safeConfig is now type Config (not Config | null)
function assertEx<T, R>(expr, errorFunc?): T;
Asserts that an expression is truthy and returns the value. Throws a custom error if the expression is falsy.
T
The type of value to check
R extends Error
The type of error to throw
Expression to be evaluated for truthiness
undefined | null | T
AssertExErrorFunc<T, R>
Function that returns a custom error instance if expression is falsy
T
The value of the expression (guaranteed to be truthy)
Custom error returned by errorFunc
// Using with a custom error
const user = assertEx(getUser(), () => new UserNotFoundError('User not found'))
function assertEx<T>(expr): T;
Asserts that an expression is truthy and returns the value. Throws an error if the expression is falsy.
T
The type of value to check
Expression to be evaluated for truthiness
undefined | null | T
T
The value of the expression (guaranteed to be truthy)
Use overload with message function instead - passing a message will soon be required
Error with a generic message
function assertEx<T>(expr, message?): T;
Asserts that an expression is truthy and returns the value. Throws an error with the provided message if the expression is falsy.
T
The type of value to check
Expression to be evaluated for truthiness
undefined | null | T
string
Error message if expression is falsy
T
The value of the expression (guaranteed to be truthy)
Replace string with () => string for consistency
Error with the provided message
Part of sdk-js
See the LICENSE file for license details
FAQs
Base functionality used throughout XY Labs TypeScript/JavaScript libraries
The npm package @xylabs/assert receives a total of 2,638 weekly downloads. As such, @xylabs/assert popularity was classified as popular.
We found that @xylabs/assert demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 5 open source maintainers collaborating on the project.
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