javascript - adding properties to array objects

Question

I'm trying to loop through a pipe delimited list passed to a function, split it out into an array based on the pipe as a separator, and then break each item out into its component parts, where the format is as follows:

"76:1167|76:1168"

so that the array would be: surveyQuestions[0] = 76:1167. And then that would be split up into : surveyQuestions[0].question = 76 and surveyQuestions[0].answer = 1167.

And this is the code I'm using, but the values come back undefined when I try to add the properties to each array item.

function answerSurvey(survey){

var surveyResults = survey.split("|");

for (var i=0;i<surveyResults.length;i++){

    var surveyResult = surveyResults[i].split(":");
    var surveyQ = surveyResult[0];
    var surveyA = surveyResult[1];
    surveyResults[i].surveyQ = surveyQ;
    surveyResults[i].surveyA = surveyA;
    console.log(surveyResults[i].surveyQ + "|" + surveyResults[i].surveyA)
}

}

answerSurvey("76:1167|76:1168");

gilly3 · Accepted Answer · 2011-09-02 22:19:58Z

3

You are trying to add a property to a string, which you cannot do. If you want the Array to contain a list of Objects, use Array.map() to transform your strings into objects:

var surveyResults = survey.split("|").map(function (result) {
    var parts = result.split(":");
    return {
        question: parts[0],
        answer: parts[1]
    };
});

It is included in most browsers, but for older versions of some browsers, you'll need to add .map() manually.

Edit: jQuery does add a map function (as noted in the comments). Tweak the code above slightly to include the array as the first parameter to $.map() and substitute the argument name for this (or shift the result argument one to the right, following index):

var surveyResults = $.map(survey.split("|"), function (i, result) {
    var parts = result.split(":");  // or this.split(":")
    return {
        question: parts[0],
        answer: parts[1]
    };
});

edited Sep 2, 2011 at 22:19

answered Sep 2, 2011 at 22:07

gilly3

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3 Comments

Jens Roland Over a year ago

Also, the asker seems to be using jQuery, which offers a cross-browser implementation: $.map(array,function)

mheavers Over a year ago

Thanks Jens - I'll probably do that

gilly3 Over a year ago

Good observation! I missed that.

Paul · Accepted Answer · 2011-09-02 22:08:30Z

1

Try this:

function answerSurvey(survey){

var surveyResults = survey.split("|");

for (var i=0;i<surveyResults.length;i++){

    var surveyResult = surveyResults[i].split(":");
    var surveyQ = surveyResult[0];
    var surveyA = surveyResult[1];
    surveyResults[i] = {};
    surveyResults[i].surveyQ = surveyQ;
    surveyResults[i].surveyA = surveyA;
    console.log(surveyResults[i].surveyQ + "|" + surveyResults[i].surveyA)
}

}

answerSurvey('76:1167|76:1168');

edited Sep 2, 2011 at 22:08

Paul

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answered Sep 2, 2011 at 22:06

Eduardo

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1 Comment

maxedison Over a year ago

Corret. To point out the only difference to the OP, it's declaring surveyResults[i] to be an object ({}). Also, the argument for answerSurvey needs quotes around it.

Paul · Accepted Answer · 2011-09-02 22:08:00Z

0

surveyResults[i] is a 'string' not an object, so you can't add properties to it.

Try this:

var surveyQ = surveyResult[0];
var surveyA = surveyResult[1];
surveyResults[i] = {};
surveyResults[i].surveyQ = surveyQ;
surveyResults[i].surveyA = surveyA;

Example: http://jsfiddle.net/Paulpro/WeJxe/

answered Sep 2, 2011 at 22:08

Paul

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