It's just reinventing the wheel.
Switch-like control structure written in TypeScript.
$ npm install --save switz
switz(subject, statement)
subject
- compared to case conditions.
statement
- function that determines cases and other behaviors.
statement
will be called with an argument context
. context
has case
, default
and matcher
methods.
context.case(condition: any, handler: (match: any) => any)
: Set case with condition and handler function.context.default(handler: () => any)
: Set default handler function.context.matcher(matcher: (subject: T, condition: any) => any)
: Set matcher function used to compare subject and each case's condition. If this returns truthy value, tha case matches.
// switz
const switz = require("switz");
switz(expr, s => {
s.matcher(switz.IncludedMatcher);
s.case(["Oranges"], () => {
console.log('Oranges are $0.59 a pound.');
});
s.case(["Apples"], () => {
console.log('Apples are $0.32 a pound.');
});
s.case(["Bananas"], () => {
console.log('Bananas are $0.48 a pound.');
});
s.case(["Cherries"], () => {
console.log('Cherries are $3.00 a pound.');
});
s.case(["Mangoes", "Papayas"], () => {
console.log('Mangoes and papayas are $2.79 a pound.');
});
s.default(() => {
console.log('Sorry, we are out of ' + expr + '.');
});
});
// Native switch
switch (expr) {
case 'Oranges':
console.log('Oranges are $0.59 a pound.');
break;
case 'Apples':
console.log('Apples are $0.32 a pound.');
break;
case 'Bananas':
console.log('Bananas are $0.48 a pound.');
break;
case 'Cherries':
console.log('Cherries are $3.00 a pound.');
break;
case 'Mangoes':
case 'Papayas':
console.log('Mangoes and papayas are $2.79 a pound.');
break;
default:
console.log('Sorry, we are out of ' + expr + '.');
}
Returns matched case's handler output.
const value1 = switz("foo", s => {
s.case("foo", () => "foo!");
s.case("bar", () => "bar!");
});
console.log(value1); // foo!
Can match subject and conditions with preset matcher. Also, can use matcher output as handler input.
import switz, {RegexpMatcher} from 'switz';
const message = switz("fooooooooooooooooooooooooooooooo", s => {
s.matcher(RegexpMatcher);
s.case(/fo{10,}/, match => `yes, ${match[0].length} "o"s.`);
s.default(() => "no");
});
console.log(message); // yes, 32 "o"s.
Can be used with type parameter in TypeScript.
const v = switz<string>("foo", s => {
s.case("foo", () => "bar");
s.case("bar", () => "baz");
s.case("fuz", () => 123); // Type unmatch ERROR!
});
Method-chainable.
switz("foo", s => s
.case("foo", () => "bar")
.case("bar", () => "baz")
);
The function switz
is a wrapper of Switch
class instance. You can use Switch
and Case
class directly if you would like to.
const {Switch, Case} = require("switz");
// Or use `import`
import {Switch, Case} from "switz";
const subject = Math.floor(Math.random() * 100);
const mySwitch = new Switch(subject);
mySwitch.setMatcher((s, c) => {
const min = c[0];
const max = c[1];
return min <= s && max >= s;
});
mySwitch.addCase(new Case([0, 50], () => "Between 0-50"));
mySwitch.addCase(new Case([50, 100], () => "Between 50-100"));
console.log(mySwitch.evaluate());
See also: test codes
First.
$ git clone
$ cd switz
$ yarn
Test.
$ yarn test
Lint.
$ yarn run lint