Why does alert(0.-5) print -5?












7















Suppose I write 0.5 as 0.-5 in unexpected way, but it can still run, my question is , what does "0." in "0.-5" do so that it can still run and prints -5?



I also tried alert(0.-5+1) , which prints -4, does javascript ignores "0." in "0.-5"?






javascript numbers







share|improve this question




















  • 2





    0. is like 0.0. Or just 0.

    – Ry-♦
    3 hours ago


















7















Suppose I write 0.5 as 0.-5 in unexpected way, but it can still run, my question is , what does "0." in "0.-5" do so that it can still run and prints -5?



I also tried alert(0.-5+1) , which prints -4, does javascript ignores "0." in "0.-5"?






javascript numbers







share|improve this question




















  • 2





    0. is like 0.0. Or just 0.

    – Ry-♦
    3 hours ago
















7












7








7


1






Suppose I write 0.5 as 0.-5 in unexpected way, but it can still run, my question is , what does "0." in "0.-5" do so that it can still run and prints -5?



I also tried alert(0.-5+1) , which prints -4, does javascript ignores "0." in "0.-5"?






javascript numbers







share|improve this question
















Suppose I write 0.5 as 0.-5 in unexpected way, but it can still run, my question is , what does "0." in "0.-5" do so that it can still run and prints -5?



I also tried alert(0.-5+1) , which prints -4, does javascript ignores "0." in "0.-5"?






javascript numbers




javascript numbers






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 1 hour ago









Charlie H

9,03342550




9,03342550










asked 3 hours ago









mmmaaammmaaa

2,2281311




2,2281311








  • 2





    0. is like 0.0. Or just 0.

    – Ry-♦
    3 hours ago
















  • 2





    0. is like 0.0. Or just 0.

    – Ry-♦
    3 hours ago










2




2





0. is like 0.0. Or just 0.

– Ry-♦
3 hours ago







0. is like 0.0. Or just 0.

– Ry-♦
3 hours ago














2 Answers
2






active

oldest

votes


















7














Trailing digits after a . are optional:






console.log(0. === 0);





So



0.-5


evalutes to



0 - 5


which is just -5. Similarly,



0.-5+1


is



0 - 5 + 1


which is



-5 + 1


or -4.






share|improve this answer































    0














    In JS you can express a number with optional decimal point. 



    x = 5.;    //5
    
x = 5. + 6.   //11





    share|improve this answer
























    • You can even do 5..toString().

      – Tvde1
      46 mins ago











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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    7














    Trailing digits after a . are optional:






    console.log(0. === 0);





    So



    0.-5


    evalutes to



    0 - 5


    which is just -5. Similarly,



    0.-5+1


    is



    0 - 5 + 1


    which is



    -5 + 1


    or -4.






    share|improve this answer




























      7














      Trailing digits after a . are optional:






      console.log(0. === 0);





      So



      0.-5


      evalutes to



      0 - 5


      which is just -5. Similarly,



      0.-5+1


      is



      0 - 5 + 1


      which is



      -5 + 1


      or -4.






      share|improve this answer


























        7












        7








        7







        Trailing digits after a . are optional:






        console.log(0. === 0);





        So



        0.-5


        evalutes to



        0 - 5


        which is just -5. Similarly,



        0.-5+1


        is



        0 - 5 + 1


        which is



        -5 + 1


        or -4.






        share|improve this answer













        Trailing digits after a . are optional:






        console.log(0. === 0);





        So



        0.-5


        evalutes to



        0 - 5


        which is just -5. Similarly,



        0.-5+1


        is



        0 - 5 + 1


        which is



        -5 + 1


        or -4.






        console.log(0. === 0);





        console.log(0. === 0);






        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 3 hours ago









        CertainPerformanceCertainPerformance

        88.9k154876




        88.9k154876

























            0














            In JS you can express a number with optional decimal point. 



            x = 5.;    //5
            
x = 5. + 6.   //11





            share|improve this answer
























            • You can even do 5..toString().

              – Tvde1
              46 mins ago
















            0














            In JS you can express a number with optional decimal point. 



            x = 5.;    //5
            
x = 5. + 6.   //11





            share|improve this answer
























            • You can even do 5..toString().

              – Tvde1
              46 mins ago














            0












            0








            0







            In JS you can express a number with optional decimal point. 



            x = 5.;    //5
            
x = 5. + 6.   //11





            share|improve this answer













            In JS you can express a number with optional decimal point. 



            x = 5.;    //5
            
x = 5. + 6.   //11






            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 2 hours ago









            Charlie HCharlie H

            9,03342550




            9,03342550













            • You can even do 5..toString().

              – Tvde1
              46 mins ago



















            • You can even do 5..toString().

              – Tvde1
              46 mins ago

















            You can even do 5..toString().

            – Tvde1
            46 mins ago





            You can even do 5..toString().

            – Tvde1
            46 mins ago


















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