@stdlib/utils-try-function NPM

Try Function

Wrap a function in a try/catch block.

Installation

npm install @stdlib/utils-try-function

Usage

var wrap = require( '@stdlib/utils-try-function' );

wrap( fcn )

Wraps a function in a try/catch block.

function fcn() {
    throw new Error( 'beep boop' );
}

var f = wrap( fcn );

var out = f();
if ( out instanceof Error ) {
    console.error( out.message );
    // => 'beep boop'
}

The returned function has the same signature as the wrapped function.

function fcn( a, b, c, d ) {
    var sum = a + b + c + d;
    if ( sum < 10 ) {
        throw new Error( 'invalid arguments. Arguments must sum to a number greater than or equal to 10.' );
    }
    return sum;
}

var f = wrap( fcn );

var out = f( 5, 6, 7, 8 );
// returns 26

out = f( 1, 2, 3, 1 );
// returns <Error>

If provided an asynchronous function, the returned function only traps errors which occur during the current event loop tick.

function fcn( a, b, clbk ) {
    if ( !a ) {
        throw new Error( 'invalid argument.' );
    }
    setTimeout( onTimeout, 0 );
    function onTimeout() {
        if ( !b ) {
            throw new Error( 'invalid argument.' );
        }
        clbk();
    }
}

function done() {
    console.log( 'beep' );
}

var f = wrap( fcn );

var out = f( null, 5, done );
// returns <Error>

out = f( true, null, done );
// returns undefined

Notes

Isolating try/catch blocks as separate wrapped functions prevents a parent scope from permanently entering optimization hell.
If a function throws a literal, the literal is serialized as a string and returned as an Error object.

Examples

var wrap = require( '@stdlib/utils-try-function' );

function beep( str ) {
    if ( typeof str !== 'string' ) {
        throw new TypeError( 'invalid argument. Must provide a string. Value: `' + str + '`.' );
    }
    return 'beep ' + str;
}

function boop( str, clbk ) {
    if ( typeof str !== 'string' ) {
        throw new TypeError( 'invalid argument. Must provide a string. Value: `' + str + '`.' );
    }
    setTimeout( done, 1000 );

    function done() {
        if ( str !== 'beep' ) {
            throw new Error( 'invalid argument. String must equal `beep`. Value: `' + str + '`.' );
        }
        clbk( str + ' boop' );
    }
}

function done( str ) {
    if ( str !== 'beep boop' ) {
        throw new Error( 'huh?' );
    }
}

// Synchronous...
var f = wrap( beep );

var out = f( 'boop' );
console.log( out );
// => 'beep boop'

out = f( null );
console.log( out.message );
// => '...'

// Asynchronous...
f = wrap( boop );

out = f( 'beep', done );
console.log( out );
// => undefined

out = f( 'foo', done );
console.log( out );
// => undefined

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.