how we can covert a string to boolean?

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How can I convert a string to boolean in JavaScript?

I have a select list with 2 options in it, yes or no, something like:

   <select size="1">
     <option value="true">yes</option>
     <option value="false">no</option>
   </select>

Now i want to use the selected value in the jquery-UI button disabled property , means :

  $("button").button({ disabled : $("select").val() });

Now my problem is that the value which we will get by $("select").val() is string and for

disabled property we need boolean. So i want to know that is there any method just like

pareInt or parseFloat by which we can convert a string to boolean ?

because of the ambiguity, you should specify what you consider true or false... By nature, all non-empty strings are true, even the string `"false"`. Do you want this to happen? be more specific please — ajax333221, Jul 04 '12 at 18:34

score 5 · Accepted Answer · answered Jul 04 '12 at 18:18

5

var value = ('true' === $("select").val() );

answered Jul 04 '12 at 18:18

insertusernamehere

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ajax333221 · Answer 2 · 2012-07-04T19:00:03.570

You can use the third one:

var num = +something; //toNumber
var str = something + ""; //toString
var bol = !!something; //toBoolean

That will turn 0, "", false, null, undefined, NaN to false, and everything else to true

But using my deduction powers, you want something like "false" -> false, for this you can use one of these:

var bol = something === "true"; //false for anything different than true
var bol = something !== "false"; //true for anything different than false

score 0 · Answer 3 · edited Jul 04 '12 at 18:37

0

Try with this code:

var myBool = myString == "true";

edited Jul 04 '12 at 18:37

VisioN

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answered Jul 04 '12 at 18:17

Aghilas Yakoub

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score 0 · Answer 4 · edited Jul 04 '12 at 18:37

0

How about writing your own?

I'm not exactly firm in JavaScript Syntax but try this:

function a(inputString)
    if(inputString == "true")
        return true;
    if(inputString == "false")
        return false;

I'm sure there are better solutions. This one is just from the top of my head.

edited Jul 04 '12 at 18:37

VisioN

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answered Jul 04 '12 at 18:18

DrEnquinox

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score 0 · Answer 5 · answered Jul 04 '12 at 18:19

0

var myBoolean = (myString === 'true') ? true : false;

answered Jul 04 '12 at 18:19

micadelli

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ternary operator not necessary, you can use the equality result directly: `var myBoolean = myString === 'true';` – ajax333221 Jul 04 '12 at 18:36
someone really -1 because my comment?, it was just a minor improvement, not really a reason to dv :/ – ajax333221 Jul 04 '12 at 18:48
@ajax333221 true, that yours and accepted answer are more elegant. Plus, don't I just hate anonymous downvoters. – micadelli Jul 04 '12 at 20:04

score 0 · Answer 6 · answered Jul 04 '12 at 18:19

0

Something like

$("select").val() == 'true'

should do the trick.

answered Jul 04 '12 at 18:19

james_bond

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score 0 · Answer 7 · answered Jul 04 '12 at 18:21

Depends how many times you want to do it. If its going to be littered throughout your code I would add in a function like:

Boolean.parse = function (str) {
  switch (str.toLowerCase ()) {
    case "true":
      return true;
    case "false":
      return false;
    default:
      throw new Error ("Boolean.parse: Cannot convert string to boolean.");
  }
};

how we can covert a string to boolean?

7 Answers7