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/try-catch-async' );

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/try-catch-async' );

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();