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38 lines
1.1 KiB
38 lines
1.1 KiB
import promiseToCallback from 'promise-to-callback';
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const callbackNoop = function (err) {
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if (err) {
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throw err;
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}
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};
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/**
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* A generator that returns a function which, when passed a promise, can treat that promise as a node style callback.
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* The prime advantage being that callbacks are better for error handling.
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*
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* @param {Function} fn - The function to handle as a callback
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* @param {Object} context - The context in which the fn is to be called, most often a this reference
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*
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*/
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export default function nodeify(fn, context) {
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return function (...args) {
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const lastArg = args[args.length - 1];
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const lastArgIsCallback = typeof lastArg === 'function';
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let callback;
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if (lastArgIsCallback) {
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callback = lastArg;
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args.pop();
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} else {
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callback = callbackNoop;
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}
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// call the provided function and ensure result is a promise
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let result;
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try {
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result = Promise.resolve(fn.apply(context, args));
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} catch (err) {
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result = Promise.reject(err);
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}
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// wire up promise resolution to callback
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promiseToCallback(result)(callback);
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};
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}
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