proto-typescript

Utility types and implementations based on JavaScript prototypes. I plan to share the features that are officially available from 2.0.0.

TypedClass

prototype methods

new TypedArray([1, 2, 3] as const).unshift(4 as const); // TypedArray<[4, 1, 2, 3]>

new TypedArray([1, 2, 3] as const).join(','); // TypedString<'1,2,3'>

The return result of 'TypeClass' returns one of the instances of TypeClass again. Therefore, those who know the grammar of JavaScript can use it immediately.

refined methods

/**
 * error case
 */
new TypedArray<'1-3'>([1, 2, 3]).refine([1, 2, 3] as const).join('-');
new TypedArray<'1-3'>([]).refine([1, 2, 3] as const).join('-');
new TypedArray<'1-3'>().refine([1, 2, 3, 4] as const).join('-');
new TypedArray<'1-3'>().refine([0, 1, 2, 3] as const).join('-');

/**
 * right case
 */
new TypedArray<'1-3'>().refine([2, 3] as const).join('-');

TypedArray, TypedNumber has the refine method, which serves to further narrow down the generic type received as a factor. This helps reduce developer mistakes, but it should be careful because it cannot guarantee actual runtime behavior.

In the future, improvements will be made at the type level.

toPrimitive method

new TypedString('abcdef').toPrimitive(); // 'abcdef'

You can change it to the primitive type of JavaScript.

const arr = [...new TypedArray([1, 2, 3, 4, 5] as const)]; // (1 | 2 | 3 | 4 | 5)[]

Iterable/Iterator is supported.