README
when-case
This is a simple syntactic sugar library that completely replaces switch/case, and has many new features, inspired by " when" in Kotlin.
Installation
npm install when-case --save
Basic Usage
Used in modern frameworks(Vue, React, NG(soon)) and typescript
import {When, when, Case, Match, NotMatch, Is, In, NotIn, InRange, NotInRange, Else} from 'when-case';
let value: string = 'someValue';
when(value,
Case(value.length > 10, () => {
console.log('hello world');
}),
Is('anotherValue', () => {
console.log('this is another value')
}),
Else(()=>{
// Do something
})
)
Basic usage, both "when" and "When" can be used.
const value = 2;
let result = when(
Case(value === 1, 1),
Case(value < 1, ' < 1'),
// You can pass in an arrow function, and take the return value as the result
Case(value > 1, _=> 1 + value)
)
console.log(result);
console:
3
Return nothing, you can just use like "if-else"
const value = 2;
when(
Case(value === 1, () => {
console.log(' = 1')
}),
//You can also use the wording of then
//when you use then continuously
//you can get the return value of the pre 'then'
Case(value < 1).then(() => {
return ' < 1';
}).then((value)=>{
console.log(value)
}),
Case(value > 1, () => {
console.log(' > 1')
}),
Else(()=>{
console.log('error!')
})
)
console:
> 1
Usage for "In" and "InRange"
const number = 72;
const arr = [159, 160, 161];
when(number,
// Input start and end range
InRange(1, 20, 'number in 1..20'),
InRange(21, 40, 'number in 21..40'),
InRange(41, 60, 'number in 41..60'),
InRange(61, 80, 'number in 61..80')
.then((res) => {
console.log(res);
return when(number,
InRange(61, 70, "number in 61..70"),
InRange(71, 80, "number in 71..80"),
);
})
.then((res) => {
console.log(res)
}),
InRange(81, 100, 'number in 81..100'),
// multiple values
In(101, 102, 105, 'number in 101..102 or 105'),
In(...arr, 'number in arr'),
)
console:
number in 61..80
number in 71..80
"Is" usage, equivalent to Switch-Case syntax without penetration
const letter = 'T';
console.log(
when(letter,
Is('A', 'letter is A'),
Is('F', 'letter is F'),
Is('M', 'letter is M'),
Is('T', 'letter is T'),
Is('Z', 'letter is Z'),
Else('letter is ?')
)
)
console:
letter is T
"Match" regular matching
when(email,
Match(/^1([358][0-9]|4[579]|66|7[0135678]|9[89])[0-9]{8}$/).then(()=>{
console.log("match phone number regexp");
}),
Match(/^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$/).then(()=>{
console.log("match email regexp");
}),
Match(/^(?=.*\d)(?=.*[a-zA-Z])(?=.*[~!@#$%^&*])[\da-zA-Z~!@#$%^&*]{8,}$/).then(()=>{
console.log("match password regexp");
}),
)
console:
match email regexp
| Name | description |
|---|---|
| Case | Perform the operations if the condition is true |
| Is | Perform the operations if it is equal to the incoming value |
| In | Contains the incoming value to perform the operation |
| InRange | Perform operations within the upper and lower limits |
| Match | The incoming value conforms to the regular operation |
| Else | Actions that will be performed by default When there are multiple Else, only the first one will be executed |
advance
| Name | description |
|---|---|
| Not | Perform the operations if it is not equal to the incoming value |
| NotIn | Not contains the incoming value to perform the operation |
| NotInRange | Perform operations without the upper and lower limits |
| NotMatch | The incoming value don't conforms to the regular operation |
| IsNull | Perform the operations if the value is 'null' |
| IsNaN | Perform the operations if the type of the value is 'number' and value is 'NaN' |
| IsUndefined | Perform the operations if the value is 'undefined' |
| BelongTo | Perform the operations if the type of value is : "object" / "undefined" / "boolean" / "number" / "string" / "array" / "function" / "symbol" |