Convert string to Boolean in javascript

Question

How to convert a string to Boolean     I tried using the constructor Boolean  false    but it s always true

User · Answer

These lines give the following output   Boolean 1  toString       true Boolean 0  toString       false

User · Answer

I would use a simple string comparison here  as far as I know there is no built in function for what you want to do  unless you want to resort to eval    which you don t    var myBool   myString     true

User · Answer

I would like to answer this to improve upon the accepted answer   To improve performance  and in real world cases where form inputs might be passing values like  true   or  false   this method will produce the best results   function stringToBool val        return  val       toLowerCase        true       JSPerf

User · Answer

See this question for reference   How can I convert a string to boolean in JavaScript   There are a few ways      Watch case sensitivity  var boolVal    string     true      or  var boolVal   Boolean  false      or  String prototype bool   function         return    true  i  test this      alert  true  bool

User · Answer

trick string to boolean conversion in javascript  e g   var bool   true   console log bool  true    false  var bool con   JSON parse bool    console log bool con  true    true

User · Answer

you can also use JSON parse   function  JSON parse  true   returns true  Boolean   JSON parse  false   return false  Boolean

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javascript var string  false  alert Boolean string   FAIL   WIN     will not work because any non-empty string is true  javascript var string  false  alert string  false toString    FAIL   WIN     works because compared with string represenation

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I am still amazed how people vote blindly for solutions that won t work  like   var myBool   myString     true     The above is so BUGGY     Not convinced  Just try myString   true  I mean the boolean true   What is the evaluation now  Opps  false   Alternative  var myString X     X  true false  true   false   whatever   myString String myString    true   console log myString      plug any value into X and check me    will always evaluate right

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Actually you don t get the meaning of Boolean method It always return true if the variable is not null or empty   var variable   some value  Boolean variable     If my variable have some value then it will  return true  else  return false You can t use Boolean as you think

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I believe the following code will do the work   function isBoolean foo        if  foo           true      foo           false             foo    foo           true         else            console log  The variable does not have a boolean value             return            return foo      Explaining the code   foo        converts the variable  foo  to a string so if it is already boolean the function will not return an invalid result    foo           true    This comparison will return true only if  foo  is equal to  true  or true  string or boolean   Note that it is case-sensitive so  True  or any other variation will result in false    foo           true      foo           false    Similarly  the sentence above will result in true only if the variable  foo  is equal to  true   true   false  or false  So any other value like  test  will return false and then it will not run the code inside the  if  statement  This makes sure that only boolean values  string or not  will be considered   In the 3rd line  the value of  foo  is finally  converted  to boolean

User · Answer

You can try this   var myBoolean   Boolean parse boolString

User · Answer

Unfortunately  I didn t find function something like Boolean ParseBool  true   which returns true as Boolean type like in C   So workaround is  var setActive    true    setActive   setActive     true    if setActive     statements else    statements

User · Answer

Depends on what you see as false in a string   Empty string  the word false  0  should all those be false or is only empty false or only the word false   You probably need to buid your own method to test the string and return true or false to be 100   sure that it does what you need

[javascript] Convert string to Boolean in javascript

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