Is true 1 and false 0 in JavaScript

Question

I was reading a good book on JavaScript    It started with       Boolean type take only two literal values  true and false  These are distinct from numeric values  so true is not equal to 1  and false is not equal to 0    However  I observed following   if 1  true    document write  oh    that s true         this is displayed     I know  that every type in JavaScript has a Boolean equivalent    But then  what s the truth

User · Answer

From the ECMAScript specification  Section 11 9 3 The Abstract Equality Comparison Algorithm      The comparison x    y  where x and y are values  produces true or   false  Such a comparison is performed as follows          If Type y  is Boolean  return the result of the comparison x    ToNumber y        Thus  in  if  1    true   true gets coerced to a Number  i e  Number true   which results in the value of 1  yielding the final if  1    1  which is true   if  0    false  is the exact same logic  since Number false     0   This doesn t happen when you use the strict equals operator     instead      11 9 6 The Strict Equality Comparison Algorithm      The comparison x     y  where x and y are values  produces true or   false  Such a comparison is performed as follows          If Type x  is different from Type y   return false

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Ah  the dreaded loose comparison operator strikes again  Never use it  Always use strict comparison      or     instead   Bonus fact  0

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When compare something with Boolean it works like following  Step 1  Convert boolean to Number   Number true     1 and Number false     0  Step 2  Compare both sides  boolean    someting  - gt  Number boolean      someting   If compare 1 and 2 with true you will get the following results  true    1 - gt  Number true      1 - gt  1     1 - gt  true   And   true    2 - gt  Number true      1 - gt  1     2 - gt  false

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It s true that true and false don t represent any numerical values in Javascript   In some languages  e g  C  VB   the boolean values are defined as actual numerical values  so they are just different names for 1 and 0  or -1 and 0    In some other languages  e g  Pascal  C    there is a distinct boolean type that is not numerical  It s possible to convert between boolean values and numerical values  but it doesn t happen automatically   Javascript falls in the category that has a distinct boolean type  but on the other hand Javascript is quite keen to convert values between different data types   For example  eventhough a number is not a boolean  you can use a numeric value where a boolean value is expected  Using if  1        works just as well as if  true          When comparing values  like in your example  there is a difference between the    operator and the     operator  The    equality operator happily converts between types to find a match  so 1    true evaluates to true because true is converted to 1  The      type equality operator doesn t do type conversions  so 1     true evaluates to false because the values are of different types

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Actually every object in javascript resolves to true if it has  a real value  as W3Cschools puts it  That means everything except     NaN  undefined  null or 0   Testing a number against a boolean with the    operator indeed is a tad weird  since the boolean gets converted into numerical 1 before comparing  which defies a little bit the logic behind the definition  This gets even more confusing when you do something like this    x000D   x000D      var fred     3     will set fred to true  x000D      var joe     0     will set joe to false x000D      alert  fred      fred      joe      joe   x000D   x000D   x000D    not everything in javascript makes a lot of sense

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Use     to equate the variables instead of         checks if the value of the variables is similar      checks if the value of the variables and the type of the variables are similar  Notice how   if 0   false        document write  oh    that s true         and   if 0  false        document write  oh    that s true         give different results

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with    you are essentially comparing whether a variable is falsey when comparing to false or truthey when comparing to true   If you use      it will compare the exact value of the variables so true will not     1

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Try the strict equality comparison   if 1     true      document write  oh    that s true         this is not displayed     The    operator does conversion from one type to another  the     operator doesn t

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In JavaScript     is pronounced  Probably Equals     What I mean by that is that JavaScript will automatically convert the Boolean into an integer and then attempt to compare the two sides    For real equality  use the     operator

[javascript] Is true == 1 and false == 0 in JavaScript?

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