remove double quotes from string using javascript

Question

I need to replace double quotes from string, in this case string declare to the variable like below

var string = "false";

I need convert like this,

var str = false;

because I need boolean value.

This is I have already tried,

var string= data.creditAllowed;
var str= string.replace(/"/g, '\\"');

but I have get like this,

str = "false";

If you're sure it's always a string "true" or "false", then just match it using `===`. — Joseph, Oct 20 '14 at 09:13
If it is all about `true` or `false`, then you can simply use `var str = (string == "true");` — Regent, Oct 20 '14 at 09:13
`var str = string === 'false' ? false : true;` would be a better solution. — Andy, Oct 20 '14 at 09:15
@Cerbrus, using that if `string` is `'false'` `str` would be `true` which is the opposite of what we want. We want `str` to be `false`. — Andy, Oct 20 '14 at 09:24

Joe · Answer 1 · 2014-10-20T16:55:15.123

1

The reason you're being down-voted is that you've misunderstood the way types are used in JavaScript. The following code:

var x = "thing";

Creates a string, containing the characters thing and binds the variable x to it. There are no quotes in the string. The quotes are a message to the parser that want to store a string.

Notice that when you log this value to the console, it puts quotes round the value to show it's a string, so it appears surrounded by quotes. These quotes are not stored.

The reason your replacement code doesn't work is that there are no quotes in the string in the first place.

If you wrote the following:

var y = "\"thing\"";

or

var z = '"thing"';

then you would have a string with quotes in it.

What you should be doing is parsing the string containing true. The quickest way is probably this:

function parseBool(input) {
  if (input == "true") { return true; }
  else if (input == "false") { return false; }
  else return null; // or false, or throw exception, or whatever
}

edited Oct 20 '14 at 16:55

answered Oct 20 '14 at 09:15

Joe

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explain the downvote please – Joe Oct 20 '14 at 09:16
That's not how you parse random input to a boolean... – Cerbrus Oct 20 '14 at 09:16
1

Good. That's not what the question asks. – Joe Oct 20 '14 at 09:17
To quote the question: "because I need boolean value". – Joe Oct 20 '14 at 09:17
1

Then just `return input === "true"`. – Cerbrus Oct 20 '14 at 09:17
2

The point of my answer isn't the best way to parse a boolean string, it's to address the misunderstanding that led to the question. If someone had this genuine question, then it's worth addressing the underlying confusion. Also, my answer makes obvious the problems with parsing bad input and forces the questioner to think about them. – Joe Oct 20 '14 at 09:19
There are multiple problems with this answer: Redundant `else` statements after returns, returning non-boolean values from a `parseBool` function when the input isn't a specific string, nor explaining why `Boolean("false")` equals `true`, etc. – Cerbrus Oct 20 '14 at 09:22

score 1 · Answer 2 · edited Oct 20 '14 at 09:42

I think you should consider why the value is "false" instead of false instead.

Where is that value assigned, and is there any reason why you can't assign it as a proper boolean?

Otherwise you can do something like this:

function isStrTrueOrFalse(string) { return !string.toLowerCase().match(/false/);}

that way any string that is "false" returns false. Any other string returns true. This is because that "str" is true. No matter what the contents is.

You could also use the i flag in the regex, instead of .toLowerCase():

function isStrTrueOrFalse(string) { return !string.match(/false/i);}

As described in comments.

You could use the `i` flag in the regex, instead of `toLowerCase()` — Cerbrus, Oct 20 '14 at 09:24

remove double quotes from string using javascript

2 Answers2