How do I compare string and boolean in Javascript?

Question

I got the Json \"false\" from server. I respond as bool but it\'s Json so it\'s in browser type is String instead of bool

Answer 1

To compare string and Boolean in JavaScript, let us see the following examples. It returns true:

false == "0"; //true
true == "1"; //true
false == ""; //true

The followings returns false:

false == "false"; //false
true == "true"; //false

In addition, try the following example too:

var data = true;
data === "true" //false
String(data) === "true" //true

https://www.tutorialspoint.com/How-do-I-compare-String-and-Boolean-in-JavaScript

Answer 2

var data = true;
data === "true" //false
String(data) === "true" //true

This works fine.

Answer 3

String.prototype.revalue= function(){
  if(/^(true|false|null|undefined|NaN)$/i.test(this)) return eval(this);
  if(parseFloat(this)+''== this) return parseFloat(this);
  return this;
}

From: http://www.webdeveloper.com/forum/showthread.php?t=147389

Actually, you just need the first "if" statement from the function -- tests to find true or false in the code and the evals it, turning it into the boolean value

Answer 4

I think you need to look at how the JSON data is being generated. You can definitely have a normal JS boolean false in JSON.

{ "value1" : false, "value2" : true }

Answer 5

If one of the operands is Boolean, the Boolean operand is converted to 1 if it is true and +0 if it is false. (from MDN Comparison Operators page)

Examples:

true == "true"; //false
true == "1"; //true
false == "false"; //false
false == ""; //true
false == "0"; //true

Answer 6

I would just explicitly check for the string "true".

let data = value === "true";

Otherwise you could use JSON.parse() to convert it to a native JavaScript value, but it's a lot of overhead if you know it's only the strings "true" or "false" you will receive.