Monthly Archives: June 2014

Use of bootbox.js for creating multiple prompts one after another

Bootbox.js is a small and handy JavaScript library which allows one to create dialog boxes using Twitter’s Bootstrap modals programmaticallly.

Basic Example:

  bootbox.prompt("What is your name?", function(result) {                
    if (result === null) {                                             
      // notify some error message
    } else {
      // do some stuff with result
    }
  });

Recently there is a requirement in my project which requires prompting user with few questions and based on user’s response process further stuff.

My first choice was to use bootbox.js’s prompt function and I went with it.

But then after some time I started to feel like “Oops! I selected wrong library here.”. I don’t know how to call another botbox.js prompt in the callback of first one without any redundancy.
Moreover, I need to store the result of each prompt’s response for later processing purpose.

Then, my team lead suggested me to use Underscore’s partial function and gave me pseudo code.

Underscore’s partial function basically defines a function named _.partial which accepts as a parameter a function and arbitrarily no. of arguments. The return value of _.partial is a new function that when called will pass both its own parameters and the initially provided arguments to the original function.

Basic Example of _.partial:

  var add = function(a, b) {
    return a + b;
  };

  var increment = _.partial(add, 1);

We can then call the increment function like this:

  var six = increment(5); // 6

For the add function in the above example, the parameter a is fixed to
the value 1. The first argument that’s passed to increment will be passed to add
as the b parameter.

The same technique I used in the implementation of invoking multiple bootbox.js prompts on
successive prompt’s callback.

Here is how I implemented it:

    var survey_pair, survey_pairs, survey_answers = {};

    // Survey type : Question
    survey_pairs = {
        name: 'What is your name?',
        age: 'How old are you (in number only)?',
        color: 'What is your favourite color?',
        movie: 'What is your favourite movie?'
    };

    function displaySurveyResults(responses) {
        var survey_results_div = $('#survey_results');
        survey_results_div.html('');
        _.each(responses, function(value, key) {
            survey_results_div.append('<li><strong>' + key + '</strong>: ' + value + '</li>');
        });
    }

    function getFirstSurvey() {
        var first_key, first_prompt = {};
        first_key = _.first(_.keys(survey_pairs));
        if (first_key) {
            first_prompt[first_key] = survey_pairs[first_key];
            delete survey_pairs[first_key];
        }
        return first_prompt;
    }

    // main functions
    function showSurvey(survey, callback) {
        // Making survey's type as fixed argument to partial
        var new_callback = _.partial(callback, _.keys(survey)[0]);

        // Calling bootbox.prompt with survey's question and
        // partial callback which has survey's type already
        // and user response will be given through the new_callback
        bootbox.prompt(_.values(survey)[0], new_callback);
    }

    function surveyCallback(survey_type, survey_response) {
        survey_answers[survey_type] = survey_response;
        survey_pair = getFirstSurvey();
        if (survey_pair && !_.isEmpty(survey_pair)) {
            showSurvey(survey_pair, surveyCallback);
        } else {
            displaySurveyResults(survey_answers);
        }
    }

    // Get first question and initiate survey
    survey_pair = getFirstSurvey();
    if (survey_pair && !_.isEmpty(survey_pair)) {
        showSurvey(survey_pair, surveyCallback);
    } else {
        displaySurveyResults(survey_answers);
    }

Here in showSurvey, I am fixing first argument of callback which refer to surveyCallback passed from showSurvey (line no. 53).
The second argument i.e. survey_response of surveyCallback(or callback in showSurvey)
will refer to bootbox.js prompt’s result(or user’s response).

Rest logic is simple. In surveyCallback I am setting survey’s response in some variable
survey_answers here and then fetching next first survey and repeating same iteration.

Click here for working demo.