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Y.Promise.each
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YUI.add('promise-each', function (Y) { | |
function isArray(obj) { | |
return Object.prototype.toString.call(obj) === '[object Array]'; | |
} | |
function isFunction(obj) { | |
return obj && (typeof obj === 'function'); | |
} | |
Y.Promise.each = function (values, fn, context) { | |
var Promise = this; | |
// down the rabbit hole... | |
return new Promise(function (resolve, reject) { | |
if (!isArray(values)) { | |
reject(new TypeError('Promise.each expects an array of values or promises')); | |
return; | |
} | |
if (!isFunction(fn)) { | |
reject(new TypeError('Promise.each expects an iterator function')); | |
return; | |
} | |
var i = 0, | |
length = values.length, | |
remain = length, | |
result = [], | |
chains; | |
function chain(index) { | |
return Promise.resolve(values[index]) | |
.then(function (value) { | |
// cache resolved value for final resolution | |
result[index] = value; | |
// call iterator without caching return values | |
fn.call(context, value, index, values); | |
if (--remain === 0) { | |
resolve(result); | |
} | |
}, reject) // reject when promise rejects | |
.catch(reject); // reject when iterator throws | |
} | |
if (length < 1) { | |
return resolve(result); | |
} | |
// start chain with first value | |
chains = chain(i++); | |
// chain the rest of the values | |
for (; i < length; i++) { | |
chains = chains.then(chain(i), reject); | |
} | |
}); | |
}; | |
}, '', { requires: ['promise'] }); |
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YUI({ | |
modules: { | |
'promise-each': { | |
fullpath: './promise-each.js', | |
requires: ['promise'] | |
} | |
} | |
}).use('promise-each', function (Y) { | |
Y.Promise.each(['foo', 'bar', Y.when('teapot'), 'baz'], function (val, idx) { | |
if (idx === 1) { | |
throw new Error('threw at index 1'); | |
} | |
Y.log('"' + val + '" at index %d' + idx); | |
}) | |
.then(function (result) { | |
Y.log(result); | |
}) | |
.catch(function (ex) { | |
Y.error(ex); | |
}); | |
}); |
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#!/usr/bin/env node | |
var path = require('path'); | |
var YUI = require('yui').YUI; | |
var Y = YUI({ | |
useSync: true, | |
modules: { | |
'promise-each': { | |
fullpath: path.join(__dirname, 'promise-each.js'), | |
requires: ['promise'] | |
} | |
} | |
}).use('promise-each'); | |
Y.Promise.each(['foo', 'bar', Y.when('teapot'), 'baz'], function (val, idx) { | |
if (idx === 1) { | |
throw new Error('BOOM at index 1'); | |
} | |
console.log('"%s" at index %d', val, idx); | |
}) | |
.then(function (result) { | |
console.log('result', result); | |
}) | |
.catch(function (ex) { | |
console.error(ex); | |
}); |
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