Here are a few question-style titles that fit the provided article: * How to Achieve Synchronous Execution with Promise Chains: A Guide to Simplified `promiseWhile` and Array Reduction Techniques * S

How to Create Synchronous Loops with Promise Chains

Problem:

Constructing a loop to ensure synchronous execution of promise calls and subsequent logging statements can be challenging. This is especially true when using libraries like Bluebird.

Solution 1 (Simplified promiseWhile Function):

<code class="javascript">var Promise = require('bluebird');

var promiseWhile = function(condition, action) {
    var resolver = Promise.defer();

    var loop = function() {
        if (!condition()) return resolver.resolve();
        return Promise.cast(action())
            .then(loop)
            .catch(resolver.reject);
    };

    loop();

    return resolver.promise;
};</code>

This simplified version of the promiseWhile function requires passing callbacks as arguments to the condition and action parameters.

Solution 2 (Using Array Reduction):

An alternative approach is to reduce an array of email addresses and make a corresponding async call for each:

<code class="javascript">function fetchUserDetails(arr) {
    return arr.reduce(function(promise, email) {
        return promise.then(function() {
            return db.getUser(email).done(function(res) {
                logger.log(res);
            });
        });
    }, Promise.resolve());
}</code>

This approach creates a flat .then() chain and maintains the original order of the responses.

Usage:

Calling fetchUserDetails takes an array of email addresses:

<code class="javascript">fetchUserDetails(arrayOfEmailAddys).then(function() {
    console.log('all done');
});</code>

This approach eliminates the need for an outer counter or condition function. The limit is determined by the length of the email array.

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