timeandreturn

A simple utility library to get the elapsed time of a block of code. Designed to easily drop into existing code with minimal changes, for easy performance profiling.

Installation

via npm

npm install timeandreturn

Usage

Say you have a section of code

// ...
let a = foo();
let b = bar();
return foobar(a, b);

You want to know how long these three lines of code take to run. You can wrap this block of code with timeAndReturn.

const timeAndReturn = require('timeandreturn').timeAndReturn;

// ...
return timeAndReturn((elapsedTime) => {
    // Do something with elapsedTime
}, () => {
    let a = foo();
    let b = bar();
    return foobar(a, b);
});

The return value of foobar is returned by timeAndReturn, so the logic of the program is unchanged, but elapsedTime is captured.

If you only want to log elapsedTime, a logTimeAndReturn variant is provided.

const logTimeAndReturn = require('timeandreturn').logTimeAndReturn;

// ...
// Prints: "() => { let a = foo(); let b = bar(); return f ..." ran for 0.00014059999999881256 seconds
return logTimeAndReturn(() => {
    let a = foo();
    let b = bar();
    return foobar(a, b);
});

Async

If block returns a Promise, callback is called when that Promise resolves.

const logTimeAndReturn = require('timeandreturn').logTimeAndReturn;

// ...
// Prints: "async () => { let a = foo(); let b = bar(); aw ..." ran for 1.000469800000079 seconds
return logTimeAndReturn(async () => {
    let a = foo();
    let b = bar();
    await waitFor1Second();
    return foobar(a, b);
});

API

/**
 * Call callback with the time taken to run block, and return the result of block
 *
 * If block returns a Promise, call callback after promise resolves.
 *
 * Elapsed time is given in milliseconds.
 */
timeAndReturn<T>(callback: (elapsedTime: number) => void, block: () => T): T

/**
 * Log the time taken to run block, and return the result of block
 */
logTimeAndReturn<T>(block: () => T): T