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Narrow types for isOfType and consolidate typeof switch in is

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This commit is contained in:
Bjorn Stromberg 2020-06-07 15:06:30 +09:00
parent 30572a045d
commit b909111f10
1 changed files with 8 additions and 12 deletions
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20
source/index.ts
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@ -98,7 +98,8 @@ function isPrimitiveTypeName(name: any): name is PrimitiveTypeName {
export type TypeName = ObjectTypeName | PrimitiveTypeName;
const {toString} = Object.prototype;
const isOfType = <T>(type: string) => (value: unknown): value is T => typeof value === type;
// eslint-disable-next-line @typescript-eslint/ban-types
const isOfType = <T extends Function | Primitive>(type: string) => (value: unknown): value is T => typeof value === type;
const getObjectType = (value: unknown): ObjectTypeName | undefined => {
const objectTypeName = toString.call(value).slice(8, -1);
@ -117,13 +118,8 @@ const getObjectType = (value: unknown): ObjectTypeName | undefined => {
const isObjectOfType = <T>(type: ObjectTypeName) => (value: unknown): value is T => getObjectType(value) === type;
function is(value: unknown): TypeName {
switch (value) {
case null:
return 'null';
case true:
case false:
return 'boolean';
default:
if (value === null) {
return 'null';
}
switch (typeof value) {
@ -133,6 +129,10 @@ function is(value: unknown): TypeName {
return 'string';
case 'number':
return 'number';
case 'boolean':
return 'boolean';
case 'function':
return 'Function';
case 'bigint':
return 'bigint';
case 'symbol':
@ -140,10 +140,6 @@ function is(value: unknown): TypeName {
default:
}
if (is.function_(value)) {
return 'Function';
}
if (is.observable(value)) {
return 'Observable';
}