filter through js objects using underscore.js

Question

I am trying to filter through this javascript object using underscore.js, but I don't know why it's not working, its meant to find any question value that has "how" in it.

  var questions = [
    {question: "what is your name"},
    {question: "How old are you"},
    {question: "whats is your mothers name"},
    {question: "where do work/or study"},
    ];

var match = _.filter(questions),function(words){ return words === "how"});

alert(match); // its mean to print out -> how old are you?

the full code is here(underscore.js already included): http://jsfiddle.net/7cFbk/

Siguza · Accepted Answer · 2015-05-15 06:31:31Z

15

You closed the function call with .filter(questions). The last ) shouldn't be there.
Filtering works by iterating over the array and calling the function with each element. Here, each element is an object {question: "..."}, not a string.
You check for equality, whereas you want to check whether the question string contains a certain string. You even want it case-insensitive.
You cannot alert objects. Use the console and console.log instead.

So: http://jsfiddle.net/7cFbk/45/

var questions = [
    {question: "what is your name"},
    {question: "How old are you"},
    {question: "whats is your mothers name"},
    {question: "where do work/or study"},
];

var evens = _.filter(questions, function(obj) {
    // `~` with `indexOf` means "contains"
    // `toLowerCase` to discard case of question string
    return ~obj.question.toLowerCase().indexOf("how");
});

console.log(evens);

edited May 15, 2015 at 6:31

Siguza

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answered Aug 12, 2012 at 19:12

pimvdb

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3 Comments

user1551482 Over a year ago

thanks works very good, how can pass these values into a html element, adding them to a div i.e. foreach question found $('divname').html('<p>' + even.obj + '<p>'); thanks :)

pimvdb Over a year ago

I think you need to elaborate a bit. But you'll need _.each I think.

Kyle Over a year ago

To others new to Javascript, and didn't quite catch the comment in the example, the '~' at the beggining of the return line is important and the full line is equivalent to "obj.question.toLowerCase().indexOf("how") >= 0" in this specific case.

David Weldon · Accepted Answer · 2012-08-12 19:24:20Z

3

Here is a working version:

var questions = [
    {question: "what is your name"},
    {question: "How old are you"},
    {question: "whats is your mothers name"},
    {question: "where do work/or study"},
];

var hasHow = _.filter(questions, function(q){return q.question.match(/how/i)});

console.log(hasHow);

issues fixed:

Parens were not correctly placed.
Use console.log instead of alert.
You should probably use a regexp to find 'how' when iterating over each question.
_filter iterates over an array. Your array contains objects, and each object contains a question. The function you pass to _filter needs to examine each object in the same way.

edited Aug 12, 2012 at 19:24

answered Aug 12, 2012 at 19:12

David Weldon

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Comments

user1975073 · Accepted Answer · 2013-02-19 07:52:33Z

0

data = {
    'data1' :{
        'name':'chicken noodle'
     },
    'data2' :{
        'name':'you must google everything'
     },
    'data3' :{
        'name':'Love eating good food'
     }
}

_.filter(data,function(i){

    if(i.name.toLowerCase().indexOf('chick') == 0){

        console.log(i);

    }else{

        console.log('error');

    }

})

answered Feb 19, 2013 at 7:52

user1975073

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