trycatchAsync

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

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();