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callbackify.ts
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callbackify.ts
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import _ from 'lodash';
import {
AsyncFn,
CallbackFn
} from '../types';
// NOTE follows closely Node.js util.callbackify
/**
* Part of `lodash-y`.
*
* Convert Promise into callback-like function.
*
* @param origFn Promise to callbackify.
* @param options Options object.
* @param [options.callbackFirst=false] Specifies if callback is a first arg.
* @param [options.errorInCallback=true] Specifies if the first arg of callback is an error.
* @param [options.keepCallback=false] Specifies if the callback arg should be passed to the Promise.
* @returns Returns a callback-like function wrapping original `fn`.
*/
export let callbackify = function(origFn: AsyncFn, options: {
callbackFirst?: boolean;
errorInCallback?: boolean;
keepCallback?: boolean;
} = {}): CallbackFn {
_.defaults(options, {
callbackFirst: false,
errorInCallback: true,
keepCallback: false
});
let fn = function(...args): void {
let origCallback;
if (options.callbackFirst) {
origCallback = _.head(args);
if (!options.keepCallback) {
args.shift();
}
} else {
origCallback = _.last(args);
if (!options.keepCallback) {
args.pop();
}
}
let callback = (...args): void => {
// eslint-disable-next-line babel/no-invalid-this
Reflect.apply(origCallback, this, args);
// origCallback(...args);
};
let onFullfilled = function(result): void {
if (options.errorInCallback) {
setTimeout(callback, 0, undefined, result);
} else {
setTimeout(callback, 0, result);
}
};
let onRejected = function(err): void {
if (options.errorInCallback) {
setTimeout(callback, 0, err);
} else {
setTimeout(callback, 0);
}
};
// eslint-disable-next-line babel/no-invalid-this
Reflect.apply(origFn, this, args).then(onFullfilled, onRejected);
// origFn(...args).then(onFullfilled, onRejected);
};
Object.setPrototypeOf(fn, Object.getPrototypeOf(origFn));
Object.defineProperties(fn, Object.getOwnPropertyDescriptors(origFn));
return fn;
};