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trycatchAsync

If a function does not return an error, invoke a callback with the function result; otherwise, invoke a callback with a value y.

Installation

npm install @stdlib/utils-async-try-catch

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var trycatchAsync = require( '@stdlib/utils-async-try-catch' );

trycatchAsync( x, y, done )

If a function x does not return an error, invokes a done callback with the function result; otherwise, invokes a done callback with a value y.

var randu = require( '@stdlib/random-base-randu' );

function x( clbk ) {
    setTimeout( onTimeout, 0 );
    function onTimeout() {
        if ( randu() > 0.5 ) {
            return clbk( null, 1.0 );
        }
        clbk( new Error( 'oops' ) );
    }
}

function done( error, result ) {
    if ( error ) {
        console.log( error.message );
    }
    console.log( result );
}

trycatchAsync( x, -1.0, done );

The function x is provided a single argument:

• clbk: callback to invoke upon function completion

The callback accepts two arguments:

• error: error object
• result: function result

The done callback is invoked upon function completion and is provided two arguments:

• error: error object
• result: either the result of x or the provided value y

If the function x does not return a truthy error argument, the error argument provided to the done callback is null. If x does return a truthy error argument, the done callback is invoked with both the error and the provided value y.

Notes

• Execution is not guaranteed to be asynchronous. To guarantee asynchrony, wrap the done callback in a function which either executes at the end of the current stack (e.g., nextTick) or during a subsequent turn of the event loop (e.g., setImmediate, setTimeout).

Examples

var randu = require( '@stdlib/random-base-randu' );
var trycatchAsync = require( '@stdlib/utils-async-try-catch' );

var i;

function next() {
    trycatchAsync( x, 'beep', done );
}

function x( clbk ) {
    setTimeout( onTimeout, 0 );
    function onTimeout() {
        if ( randu() > 0.9 ) {
            return clbk( null, 'BOOP' );
        }
        clbk( new Error( 'oops' ) );
    }
}

function done( error, result ) {
    if ( error ) {
        console.log( error.message );
    }
    i += 1;
    console.log( result );
    if ( i < 100 ) {
        return next();
    }
}

i = 0;
next();

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See Also

• @stdlib/utils-try-catch: if a function does not throw, return the function return value; otherwise, return y.
• @stdlib/utils-async/try-then: if a function does not return an error, invoke a callback with the function result; otherwise, invoke a second function.

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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.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.