Convert a negative number to a positive one in JavaScript

Question

Is there a math function in JavaScript that converts numbers to positive value

User · Answer

var posNum    num  lt  0    num   -1   num     if num is negative multiple by negative one        I find this solution easy to understand

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The minus sign  -  can convert positive numbers to negative numbers and negative numbers to positive numbers  x -y is visual sugar for x  y -1     var y   -100  var x  - y

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You can use   operator that logically converts the number to negative and adds 1 to the negative    x000D   x000D  var x   3  x000D  x     x   1   x000D  console log x  x000D     result   -3 x000D   x000D   x000D

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If you d like to write interesting code that nobody else can ever update  try this    --x

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For a functional programming Ramda has a nice method for this  The same method works going from positive to negative and vice versa   https   ramdajs com docs  negate

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You could use this     Math abs x    Math  abs     MDN

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unsigned value   Math abs signed value

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Math abs x  or if you are certain the value is negative before the conversion just prepend a regular minus sign  x   -x

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My minimal approach   For converting negative number to positive  amp  vice-versa  x000D   x000D  var num   -24  x000D  num -  num 2  x000D  console log num  x000D     result   24 x000D   x000D   x000D

User · Answer

I did something like this myself   num lt 0 num  -1       It checks if the number is negative and if it is  multiply with -1 This does return a value  its up to you if you capture it  In case you want to assign it to something  you should probably do something like   var out   num lt 0 num  -1 num    I think someone already mentioned this variant    But it really depends what your goal is  For me it was simple  make it positive if negative  else do nothing  Hence the    in the code  In this case i used tertiary operator cause I wanted to  it could very well be   if num lt 0 num  -1    I saw the bitwise solution here and wanted to comment on that one too    --num    Drawback for this is that num original value will be reduced by 1   This soultion is very fancy in my opinion  we could rewrite it like this     num   num-1     In simple terms  we take the negative number  take one away from it and then bitwise invert it  If we had bitwise inverted it normally we would get a value 1 too small  You can also do this    num 1    Wont change the actual num value  merely returns the new value   That will do the same but will invert first and then add 1 to the positive number  Although you CANT do this    num      Wont display the right value    That will not work cause of precedence  postfix operators such as num   would be evaluated before   and the reason prefix   num wouldnt work even though it is on the same precedence as bitwise NOT     is cause it is evaluated from right to left  I did try to swap them around but it seems that prefix is a little finicky compared to bitwise NOT  The  1 will work because     has a higher precedence and will be evaluated later   I found that solution to be rather fun and decided to expand on it as it was just thrown in there and post people looking at it were probably ignoring it  Although yes  it wont work with floats   My hopes are that this post hasn t moved away from the original question

User · Answer

What about x    -1  I like its simplicity

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If you want the number to always be positive no matter what you can do this   function toPositive n       if n  lt  0           n   n   -1            return n    var a   toPositive 2       2 var b   toPositive -2      2   You could also try this  but i don t recommended it   function makePositive n       return Number  n -n  toString   replace  -           var a   makePositive 2       2 var b   makePositive -2      2   The problem with this is that you could be changing the number to negative  then converting to string and removing the - from the string  then converting back to int  Which I would guess would take more processing then just using the other function     I have tested this in php and the first function is faster  but sometimes JS does some crazy things  so I can t say for sure

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Multiplying by  -1  is the fastest way to convert negative number to positive  But you have to be careful not to convert my mistake a positive number to negative  So additional check is needed     Then Math abs  Math floor and parseInt is the slowest     https   jsperf com test-parseint-and-math-floor-and-mathabs 1

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Negative to positive  var X   -10   var number   Math abs X         result 10   Positive to negative  var X   10   var number    X   -1           result -10

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I know another way to do it  This technique works negative to positive  amp  Vice Versa  var x   -24  var result   x   -1    Vice Versa   var x   58  var result   x   -1    LIVE CODE    x000D   x000D     NEGATIVE TO POSITIVE                                             x000D  var x   -24  x000D  var result   x   -1  x000D  console log result   x000D   x000D     VICE VERSA                                                       x000D  var x   58  x000D  var result   x   -1  x000D  console log result   x000D   x000D     FLOATING POINTS                                                  x000D  var x   42 8  x000D  var result   x   -1  x000D  console log result   x000D   x000D     FLOATING POINTS VICE VERSA                                       x000D  var x   -76 8  x000D  var result   x   -1  x000D  console log result   x000D   x000D   x000D

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I know this is a bit late  but for people struggling with this  you can use the following functions    Turn any number positive  let x    54  let y   -54  let resultx    Math abs x       54 let resulty    Math abs y       54  Turn any number negative  let x    54  let y   -54  let resultx   -Math abs x      -54 let resulty   -Math abs y      -54  Invert any number  let x    54  let y   -54  let resultx   - x              -54 let resulty   - y               54

[javascript] Convert a negative number to a positive one in JavaScript

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