Convert boolean result into number integer

Question

I have a variable that stores false or true  but I need 0 or 1 instead  respectively  How can I do this

User · Answer

Imho the best solution is   fooBar   0   This is used in asm js to force integer type

User · Answer

I was just dealing with this issue in some code I was writing  My solution was to use a bitwise and   var j   bool  amp  1    A quicker way to deal with a constant problem would be to create a function  It s more readable by other people  better for understanding at the maintenance stage  and gets rid of the potential for writing something wrong   function toInt  val         return val  amp  1     var j   toInt bool     Edit - September 10th  2014  No conversion using a ternary operator with the identical to operator is faster in Chrome for some reason  Makes no sense as to why it s faster  but I suppose it s some sort of low level optimization that makes sense somewhere along the way   var j   boolValue     true   1   0    Test for yourself  http   jsperf com boolean-int-conversion 2  In FireFox and Internet Explorer  using the version I posted is faster generally   Edit - July 14th  2017  Okay  I m not going to tell you which one you should or shouldn t use  Every freaking browser has been going up and down in how fast they can do the operation with each method  Chrome at one point actually had the bitwise  amp  version doing better than the others  but then it suddenly was much worse  I don t know what they re doing  so I m just going to leave it at who cares  There s rarely any reason to care about how fast an operation like this is done  Even on mobile it s a nothing operation   Also  here s a newer method for adding a  toInt  prototype that cannot be overwritten   Object defineProperty Boolean prototype   toInt     value  function         return this  amp  1

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I created a JSperf comparison of all suggested answers   TL DR - the best option for all current browsers is   val   0       Update   It seems like these days they are all pretty identical  except that the Number   function is the slowest  while the best being val     true   1   0

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The unary   operator will take care of this   var test   true      test     1 test   false      test     0   You ll naturally want to sanity-check this on the server before storing it  so that might be a more sensible place to do this anyway  though

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Javascript has a ternary operator you could use   var i   result   1   0

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Use the unary   operator  which converts its operand into a number     true     1   false     0   Note  of course  that you should still sanitise the data on the server side  because a user can send any data to your sever  no matter what the client-side code says

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TL DR  Avoid Number constructor  unary    use a simple if all the time  resort to bool   0 or 1   bool if benchmarks in your project do better this way  This is quite an old question  and there exist many valid answers  Something I ve noticed is that all benchmarks here are irrelevant - none take into account branch prediction  Also  nowadays  JS engines don t simply interpret the code  they JIT compile it to native machine code and optimize it prior to execution  This means that  besides branch prediction  the compiler can even substitute expressions with their final value  Now  how do these 2 factors affect the performance of  well  boolean to integer conversion  Let s find out  Before we get into the benchmarks  it is important to know what we benchmark  For the conversion  we re using the following seven conversion methods   Number constructor  Number bool  If statement  ternary used   bool   1   0 Unary operator     bool Bitwise OR  bool   0 Bitwise AND  bool  amp  1 Bitwise double NOT    bool Number multiplication  bool   1   quot Conversion quot  means converting false to 0 and true to 11  Each conversion method is ran 100000 times  measuring operations millisecond  In the following tables  conversion methods will be grouped to their results accordingly  The results are from my machine  which features an AMD Ryzen 7 4800HS as its CPU  The first benchmark converts the constant true      Method Edge Chromium  V8  Firefox  Spidermonkey      Number bool  83103 1088   bool   1   0 83073 7732    bool 83372 1043   bool   0 83479 9344   bool  amp  1 83242 9354     bool 83293 9316   bool   1 83504 9316     Interesting  V8 shows some huge numbers  all of them approximately the same  Spidermonkey doesn t really shine  but we can see that the bitwise and multiplication tricks come first  and the ternary if second  What are the takeaways  Chrome browsers manage to replace our conversions with simply the value 1  This optimization will take place where we can mentally replace the boolean to a constant value  That above isn t a situation we ll ever encounter in real projects  So let s change our variables  the bool is now Math random    lt  0 5  This yields a 50  chance of true  50  of false  Do our results change  Let s run this benchmark to see      Method Edge Chromium  V8  Firefox  Spidermonkey      Number bool  2405 662   bool   1   0 1482 1580    bool 2386 673   bool   0 2391 2499   bool  amp  1 2409 2513     bool 2341 2493   bool   1 2398 2518     The results are more consistent now  We see similar numbers for ternary if  bitwise  and multiplication methods  but the Number constructor and unary   perform better on V8  We can presume from the numbers that V8 replaces them with whatever instructions it s using for the bitwise tricks  but in Spidermonkey those functions do all the work  We haven t still tackled one factor we mentioned above  branch prediction  Let s change  in this benchmark  our boolean variable to Math random    lt  0 01  which means 1  true  99  false      Method Edge Chromium  V8  Firefox  Spidermonkey      Number bool  2364 865   bool   1   0 2352 2390    bool 2447 777   bool   0 2421 2513   bool  amp  1 2400 2509     bool 2446 2501   bool   1 2421 2497     Unexpected  Expected  I d say the latter  because in this case branch prediction was successful in almost all cases  given the tiny difference between the ternary if and bitwise hacks  All other results are the same  not much else to say here  This endeavour brings us back to the original question  how to convert bool to int in Javascript  Here are my suggestions   Avoid Number bool  and  bool  These 2 methods do a lot of work under the hood  and even though Chrome managed to optimize them in our benchmarks  Firefox did not  and there might be some situations where these optimizations won t be done by the compiler  Besides that  not everyone s on Chrome  I still have to put up with that  don t you     Use if statements  in general  Don t get smart - the browser will do better  usually  and usually means most of the situations  They are the most readable and clear out of all the methods here  While we re at readability  maybe use if  bool  instead of that ugly ternary  I wish Javascript had what Rust or Python have    Use the rest when it s truly necessary  Maybe benchmarks in your project perform sub-standard  and you found that a nasty if causes bad performance - if that s the case  feel free to get into branchless programming  But don t go too deep in that rabbit hole  nobody will benefit from things like -1    a  lt  b    1    a  gt  b   believe me   I will be forever grateful to you for reading until the end - this is my first longer  significant StackOverflow answer and it means the world to me if it s been helpful and insightful  If you find any errors  feel free to correct me    Defined the conversion because it s not truly clear what boolean to integer means  For example  Go does not support this conversion at all

User · Answer

try  val 1    x000D   x000D  let t true  x000D  let f false  x000D   x000D  console log t 1   x000D  console log f 1  x000D   x000D   x000D

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let integerVariable   booleanVariable   1

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When JavaScript is expecting a number value but receives a boolean instead it converts that boolean into a number  true and false convert into 1 and 0 respectively  So you can take advantage of this    x000D   x000D  var t   true  x000D  var f   false  x000D   x000D  console log t 1      t 1     1 x000D  console log f 1      f 1     0  x000D   x000D  console log  t      0 t     1 or shortened to  t     1 x000D  console log  f     0 f     0 or shortened to  f     0 x000D   x000D   x000D    Further reading Type Conversions Chapter 3 8 of The Definitive Guide to Javascript

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I have tested all of this examples  I did a benchmark  and finally I recommend you choose the shorter one  it doesn t affect in performance      Runned in Ubuntu server 14 04  nodejs v8 12 0 - 26 10 18       let i   0  console time  TRUE test1       i 0      for  i lt 100000000 i i 1           true   1   0        console timeEnd  TRUE test1     console time  FALSE test2       i 0      for  i lt 100000000 i i 1           false   1   0        console timeEnd  FALSE test2    console log  ----------------------------    console time  TRUE test1 1       i 0      for  i lt 100000000 i i 1           true     true   1   0        console timeEnd  TRUE test1 1     console time  FALSE test2 1       i 0      for  i lt 100000000 i i 1           false     true   1   0        console timeEnd  FALSE test2 1    console log  ----------------------------    console time  TRUE test3       i 0      for  i lt 100000000 i i 1           true   0        console timeEnd  TRUE test3    console time  FALSE test4       i 0      for  i lt 100000000 i i 1           false   0        console timeEnd  FALSE test4    console log  ----------------------------    console time  TRUE test5       i 0      for  i lt 100000000 i i 1           true   1        console timeEnd  TRUE test5    console time  FALSE test6       i 0      for  i lt 100000000 i i 1           false   1        console timeEnd  FALSE test6    console log  ----------------------------    console time  TRUE test7       i 0      for  i lt 100000000 i i 1           true  amp  1        console timeEnd  TRUE test7    console time  FALSE test8       i 0      for  i lt 100000000 i i 1           false  amp  1        console timeEnd  FALSE test8    console log  ----------------------------    console time  TRUE test9       i 0      for  i lt 100000000 i i 1            true        console timeEnd  TRUE test9    console time  FALSE test10       i 0      for  i lt 100000000 i i 1            false        console timeEnd  FALSE test10    console log  ----------------------------    console time  TRUE test9 1       i 0      for  i lt 100000000 i i 1           0 true        console timeEnd  TRUE test9 1    console time  FALSE test10 1       i 0      for  i lt 100000000 i i 1           0 false        console timeEnd  FALSE test10 1    console log  ----------------------------    console time  TRUE test9 2       i 0      for  i lt 100000000 i i 1           -true -1        console timeEnd  TRUE test9 2    console time  FALSE test10 2       i 0      for  i lt 100000000 i i 1           -false -1        console timeEnd  FALSE test10 2    console log  ----------------------------    console time  TRUE test9 3       i 0      for  i lt 100000000 i i 1           true-0        console timeEnd  TRUE test9 3    console time  FALSE test10 3       i 0      for  i lt 100000000 i i 1           false-0        console timeEnd  FALSE test10 3    console log  ----------------------------    console time  TRUE test11       i 0      for  i lt 100000000 i i 1           Number true         console timeEnd  TRUE test11    console time  FALSE test12       i 0      for  i lt 100000000 i i 1           Number false         console timeEnd  FALSE test12    console log  ----------------------------    console time  TRUE test13       i 0      for  i lt 100000000 i i 1           true   0        console timeEnd  TRUE test13    console time  FALSE test14       i 0      for  i lt 100000000 i i 1           false   0        console timeEnd  FALSE test14    console log  ----------------------------    console time  TRUE test15       i 0      for  i lt 100000000 i i 1           true   0        console timeEnd  TRUE test15    console time  FALSE test16       i 0      for  i lt 100000000 i i 1           false   0        console timeEnd  FALSE test16    console log  ----------------------------    console time  TRUE test17       i 0      for  i lt 100000000 i i 1           true   0        console timeEnd  TRUE test17    console time  FALSE test18       i 0      for  i lt 100000000 i i 1           false   0        console timeEnd  FALSE test18    console log  ----------------------------    console time  TRUE test19       i 0      for  i lt 100000000 i i 1           true  gt  gt  0        console timeEnd  TRUE test19    console time  FALSE test20       i 0      for  i lt 100000000 i i 1           false  gt  gt  0        console timeEnd  FALSE test20    console log  ----------------------------    console time  TRUE test21       i 0      for  i lt 100000000 i i 1           true  gt  gt  gt  0        console timeEnd  TRUE test21    console time  FALSE test22       i 0      for  i lt 100000000 i i 1           false  gt  gt  gt  0        console timeEnd  FALSE test22    console log  ----------------------------    console time  TRUE test23       i 0      for  i lt 100000000 i i 1           true  lt  lt  0        console timeEnd  TRUE test23    console time  FALSE test24       i 0      for  i lt 100000000 i i 1           false  lt  lt  0        console timeEnd  FALSE test24    console log  ----------------------------    console time  TRUE test25       i 0      for  i lt 100000000 i i 1             true        console timeEnd  TRUE test25    console time  FALSE test26       i 0      for  i lt 100000000 i i 1             false        console timeEnd  FALSE test26    console log  ----------------------------    console time  TRUE test25 1       i 0      for  i lt 100000000 i i 1            true -1-1        console timeEnd  TRUE test25 1    console time  FALSE test26 1       i 0      for  i lt 100000000 i i 1            false -1-1        console timeEnd  FALSE test26 1    console log  ----------------------------    console time  TRUE test27       i 0      for  i lt 100000000 i i 1           true 1        console timeEnd  TRUE test27    console time  FALSE test28       i 0      for  i lt 100000000 i i 1           false 1        console timeEnd  FALSE test28     Result   TRUE test1  93 301ms FALSE test2  102 854ms ---------------------------- TRUE test1 1  118 979ms FALSE test2 1  119 061ms ---------------------------- TRUE test3  97 265ms FALSE test4  108 389ms ---------------------------- TRUE test5  85 854ms FALSE test6  87 449ms ---------------------------- TRUE test7  83 126ms FALSE test8  84 992ms ---------------------------- TRUE test9  99 683ms FALSE test10  87 080ms ---------------------------- TRUE test9 1  85 587ms FALSE test10 1  86 050ms ---------------------------- TRUE test9 2  85 883ms FALSE test10 2  89 066ms ---------------------------- TRUE test9 3  86 722ms FALSE test10 3  85 187ms ---------------------------- TRUE test11  86 245ms FALSE test12  85 808ms ---------------------------- TRUE test13  84 192ms FALSE test14  84 173ms ---------------------------- TRUE test15  81 575ms FALSE test16  81 699ms ---------------------------- TRUE test17  81 979ms FALSE test18  81 599ms ---------------------------- TRUE test19  81 578ms FALSE test20  81 452ms ---------------------------- TRUE test21  115 886ms FALSE test22  88 935ms ---------------------------- TRUE test23  82 077ms FALSE test24  81 822ms ---------------------------- TRUE test25  81 904ms FALSE test26  82 371ms ---------------------------- TRUE test25 1  82 319ms FALSE test26 1  96 648ms ---------------------------- TRUE test27  89 943ms FALSE test28  83 646ms

User · Answer

I prefer to use the Number function  It takes an object and converts it to a number   Example   var myFalseBool   false  var myTrueBool   true   var myFalseInt   Number myFalseBool   console log myFalseInt     0    var myTrueInt   Number myTrueBool   console log myTrueInt     1     You can test it in a jsFiddle

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I just came across this shortcut today      true      false   People much smarter than I can explain    http   james padolsey com javascript double-bitwise-not

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The typed way to do this would be   Number true     1 Number false     0

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You can also add 0  use shift operators or xor   val   0  val   0  val  gt  gt  0  val  gt  gt  gt  0  val  lt  lt  0    These have similar speeds as those from the others answers

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You could do this by simply extending the boolean prototype  Boolean prototype intval   function   return   this    It is not too easy to understand what is going on there so an alternate version would be   Boolean prototype intval   function   return  this    true  1 0    having done which you can do stuff like  document write true intval       When I use booleans to store conditions I often convert them to bitfields in which case I end up using an extended version of the prototype function  Boolean prototype intval   function places     places     undefined     typeof places   0 places    return    this   lt  lt  places     with which you can do   document write true intval 2     which produces 4 as its output

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allows you to apply this on a variable even when it s undefined     undefined       0    false           0    true            1       lt boolean expression gt       1 if it evaluates to true  0 otherwise

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if you want integer x value change if 1 to 0 and if 0 to 1 you can use   x   1    2

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In my context  React Native where I am getting opacity value from boolean  the easiest way  Use unary    operator     true     1   false     0   This converts the boolean into number   style   opacity    isFirstStep

[javascript] Convert boolean result into number/integer

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