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On this page
  • guardDefined()
  • Generic type variables
  • Parameters
  • Return type
  • Returns
  • Example usage

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  1. Guard

guardDefined()

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Last updated 3 years ago

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guardDefined()

Guards the value to be defined, not .

guard-defined.func.ts
const guardDefined = <Type, Payload extends object = object>(
  value: Defined<Type>,
  callback?: ResultCallback<Defined<Type>, Payload>,
  payload?: Payload
): value is Defined<Type> => isDefined(value, callback, payload);

Generic type variables

Type

A generic type variable Type indicates captured type of the given via the and the parameter of the provided function type.

Payloadextendsobject=object

The Payload generic type variable constrained by indicates the type of optional parameter of the supplied function and optional parameter of the function from which it captures its value.

Parameters

value: Defined<Type>

The value of generic type , undefined type captured from itself to guard against .

callback?: ResultCallback<Defined<Type>, Payload>

payload?: Payload

Return type

value is Defined<Type>

Returns

Example usage

// Example usage.
import { guardDefined } from '@angular-package/type';

let letFirstName = 'my name';
guardDefined(letFirstName); // true; return type `value is string`

const firstName = 'my const name';
guardDefined(firstName); // true; return type `value is string`

The optional callback of type with parameters, the that has been checked, the of this check, and of generic type variable with optional properties from the provided , to handle them before the return. By default, it uses function.

An optional of the generic type variable is assigned to the of the given function.

The return type is a as the result of its statement indicating the is a generic type that takes a generic type variable of value by default equal to the type captured from the supplied parameter excepts which changes to .

The return value is a indicating whether the is defined.

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