Question mark and colon in JavaScript

Question

I came across the following line  hsb s   max    0   255   delta   max   0    What do the   and   mean in this context

User · Answer

Properly parenthesized for clarity  it is   hsb s    max    0     255   delta   max    0    meaning return either   255 delta max if max    0 0 if max    0

User · Answer

hsb s   max    0   255   delta   max   0      is a ternary operator  It works like an if in conjunction with the       means not equals  So  the long form of this line would be  if  max    0      if max is not zero   hsb s   255   delta   max    else     hsb s   0

User · Answer

It is called the Conditional Operator  which is a ternary operator    It has the form of  condition   value-if-true   value-if-false Think of the   as  then  and   as  else    Your code is equivalent to  if  max    0    hsb s   255   delta   max  else   hsb s   0

User · Answer

Be careful with this   A -1 evaluates to true although -1    true and -1    false   Trust me  I ve seen it happen   so   -1    true side     false side    evaluates to  true side

User · Answer

This is probably a bit clearer when written with brackets as follows   hsb s    max    0     255   delta   max    0    What it does is evaluate the part in the first brackets  If the result is true then the part after the   and before the   is returned  If it is false  then what follows the   is returned

User · Answer

is a short-hand condition for else    and if     problems  So your code is interchangeable to this   if max    0          hsb s   225   delta   max   else          hsb s   0     MDN - Conditional  Ternary  Operator

User · Answer

isn t this the ternary operator   var x  expression   true false

[javascript] Question mark and colon in JavaScript

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