cont-flow-expr
What if you could write something like:
const value = if (condition) {
optionA;
} else {
optionB;
}Enter, cont-flow-expr:
import { fi } from "cont-flow-expr";
const value = fi(condition)
.then(optionA)
.else(optionB);API
if-elseif*-else
A basic if-else expression can be written as:
import { fi } from "cont-flow-expr";
// or: import fi from "cont-flow-expr/if";
const value = fi(condition)
.then(optionA)
.else(optionB);An if-elseif-else expression can be written as:
import { fi } from "cont-flow-expr";
const value =
fi(condition1).then(optionA)
.elseIf(condition2).then(optionB)
// .elseIf(conditionN-1).then(optionN-1)
.else(optionZ);with arbitrarily many uses of .elseIf().then().
Branches can also be evaluated lazily, which can mixed with normal branches arbitrarily:
import { fi } from "cont-flow-expr";
const value =
fi(condition1).then(optionA)
.elseIf(condition2).thenDo(() => optionB)
.else(optionC);See cont-flow-expr.if for more details.
switch-case*-default
A switch-case expression can be written as:
import { hctiws } from "cont-flow-expr";
// or: import hctiws from "cont-flow-expr/switch";
const value = hctiws(query)
.case(candidate1).then(optionA)
.case(candidate2).then(optionB)
// .case(candidateN-1).then(optionN-1)
.default(optionZ);with arbitrarily many uses of .case().then().
Branches can also be evaluated lazily, which can mixed with normal branches arbitrarily:
import { hctiws } from "cont-flow-expr";
const value = hctiws(query)
.case(candidate1).thenDo(() => optionA)
.case(candidate2).then(optionB)
.defaultDo(() => optionC);See cont-flow-expr.switch for more details.
try-catch
A try-catch expression can be written as:
import { yrt } from "cont-flow-expr";
// or: import yrt from "cont-flow-expr/try";
const value = yrt(() => {
// Potentially failing commands
return optionA;
}).catch(() => {
// Recovering commands
return optionB;
});See cont-flow-expr.try for more details.
TypeScript
TypeScript support is included and can be used to ensure all branches of a given expression evaluate to the same type (union). For this to work you have to provide a type annotation. For example:
import { fi } from "cont-flow-expr";
const condition = true, optionA = "foo", optionB = "bar";
const aString = fi<string>(condition)
.then(optionA)
.else(optionB);Benchmarks
The benchmarks in this project - which are powered by Benchmark.js - can be used to compare this library against vanilla JavaScript as well as alternative libraries. Here's a sample:
if-else
vanilla x 1,409,198,725 ops/sec ±0.16% (97 runs sampled)
cont-flow-expr x 68,040,893 ops/sec ±0.53% (96 runs sampled)
dolla-if x 60,359,107 ops/sec ±0.36% (99 runs sampled)
switch-case
vanilla x 1,411,831,771 ops/sec ±0.15% (98 runs sampled)
cont-flow-expr x 15,601,299 ops/sec ±0.83% (94 runs sampled)
try-catch
vanilla x 1,401,337,499 ops/sec ±0.15% (91 runs sampled)
cont-flow-expr x 70,774,351 ops/sec ±0.20% (96 runs sampled)License
The source code is licensed under the ISC license. The documentation text is licensed under CC BY 4.0.