curfew-promise v1.1.0

curfew-promise

A wrapper around a sync or async function that creates a promise. This promise will reject itself if the wrapped function took too long to resolve.

Installation

$ npm i curfew-promise

Syntax

const curfewPromise = require("curfew-promise");

// curfew is the time in milliseconds. 
// func is the function (sync or async) to run.
// ...args are any arguments for func
// func will run until it finishes or until curfew has elapsed.
curfewPromise(curfew, func, ...args);

// This will act solely as a timer. 
// It will resolve after curfew has elapsed.
curfewPromise(curfew);

Example 1

const curfewPromise = require("curfew-promise");

// This will give a curfew of 1 second to add two numbers.
// The result will (most likely) be a resolved promise with value 9.
curfewPromise(1000, (num1, num2) => {
    return num1 + num2;
}, 5, 4);

Example 2

const curfewPromise = require("curfew-promise");

// The function will recursively generate Fibonacci numbers.
// It pauses for 1 second before each number.
function fib(num1, num2, amount) {
    const next = num1 + num2;
    console.log(next);

    if(amount-- > 1)
        setTimeout(fib, 1000, num2, next, amount);
}

// This will give a curfew of 10 seconds to generate 8 Fibonacci numbers.
curfewPromise(10000, fib, 1, 1, 8);

Example 3

const curfewPromise = require("curfew-promise");

async function test() {
    ...

    // By excluding any function, the promise will only act as a timer.
    // This line will pause the test() function for 1000 milliseconds.
    await curfewPromise(1000);

    ...
}

Warning Example

I found this out the hard way while trying to test this. Since JavaScript isn't actually mutli-threaded, if you have a one line async function that is very slow, it will be treated like a synchronous function. This is because once the line begins, JavaScript will wait for it to end before moving on. If you'd like to know more, feel free to read my blog post about it.

const curfewPromise = require("curfew-promise");

// This will run forever and never even create a promise
curfewPromise(0, async () => { while(true); });

// This will wait until the for loop completes before creating a promise.
curfewPromise(0, async () => {
    for(i = 0; i < 10000000; i += .01);
});