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If a function does not return an error, invoke a callback with the function result; otherwise, invoke a second function.
import trythenAsync from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-async-try-then@esm/index.mjs';If a function x does not return an error, invokes a done callback with the function result; otherwise, invokes a second function y.
import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@esm/index.mjs';
function x( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
if ( randu() > 0.5 ) {
return clbk( null, 1.0 );
}
clbk( new Error( 'oops' ) );
}
}
function y( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
clbk( null, -1.0 );
}
}
function done( error, result ) {
if ( error ) {
throw error;
}
console.log( result );
}
trythenAsync( x, y, done );The function x is provided a single argument:
clbk: callback to invoke upon function completion
The callback function accepts any number of arguments, with the first argument reserved for providing an error. If the error argument is falsy, the done callback is invoked with its first argument as null and all other provided arguments.
import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@esm/index.mjs';
function x( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
clbk( null, 1.0, 2.0, 3.0 );
}
}
function y( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
clbk( null, 4.0, 5.0, 6.0 );
}
}
function done( error, a, b, c ) {
if ( error ) {
throw error;
}
console.log( a, b, c );
}
trythenAsync( x, y, done );If the error argument is truthy, the function invokes y. The number of arguments provided to y depends on the function's length. If y is a unary function, y is provided a single argument:
clbk: callback to invoke upon function completion
Otherwise, y is provided two arguments:
error: the error fromxclbk: callback to invoke upon function completion
The callback function accepts any number of arguments, with the first argument reserved for providing an error. If the error argument is falsy, the done callback is invoked with its first argument equal to null and all other provided arguments. If the error argument is truthy, the done callback is invoked with only the error argument provided by y.
import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@esm/index.mjs';
function x( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
if ( randu() > 0.5 ) {
return clbk( null, 1.0, 2.0, 3.0 );
}
clbk( new Error( 'beep' ) );
}
}
function y( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
if ( randu() > 0.5 ) {
return clbk( null, 4.0, 5.0, 6.0 );
}
clbk( new Error( 'boop' ) );
}
}
function done( error, a, b, c ) {
if ( error ) {
console.error( error.message );
}
console.log( a, b, c );
}
trythenAsync( x, y, done );- Execution is not guaranteed to be asynchronous. To guarantee asynchrony, wrap the
donecallback 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).
<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">
import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@esm/index.mjs';
import ceil from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-ceil@esm/index.mjs';
import repeatString from 'https://cdn.jsdelivr.net/gh/stdlib-js/string-repeat@esm/index.mjs';
import trythenAsync from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-async-try-then@esm/index.mjs';
var i;
function next() {
trythenAsync( x, y, done );
}
function x( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
if ( randu() > 0.9 ) {
return clbk( null, repeatString( 'BOOP', ceil( randu()*3.0 ) ) );
}
clbk( new Error( 'oops' ) );
}
}
function y( clbk ) {
setTimeout( onTimeout, 0 );
function onTimeout() {
clbk( null, repeatString( 'beep', ceil( randu()*5.0 ) ) );
}
}
function done( error, result ) {
if ( error ) {
throw error;
}
i += 1;
console.log( result );
if ( i < 100 ) {
return next();
}
}
i = 0;
next();
</script>
</body>
</html>@stdlib/utils-async/try-catch: if a function does not return an error, invoke a callback with the function result; otherwise, invoke a callback with a valuey.@stdlib/utils-try-then: if a function does not throw, return the function return value; otherwise, return the return value of a second function.
This package is part of stdlib, a standard library 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.
See LICENSE.
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