Javascript syntax errors with basic expressions

Hello,

There is one key thing wrong in your script, but before I get to that, there are a couple other things I should mention:

The indentation level of open { and closed } should be the same:

 if (comparison) {
 }
 //NOT
 if (comparison) {
     }

Absolutely everyone is in agreement, that you should leave a space between ) and {:

 if (comparison) {
 //OR
 if ( comparison ) {
 //BUT NEVER
 if(comparison){

Now onto the actual problem:

In UnityScript, just like in C#, there are different types of operators, such as x.y or < etc. These are all about using special syntax to achieve certain things.

There are primary:

 //Member access with the "." operator
 x.y
 //Invoke methods
 f(x)
 //Type casting
 x as y
 //increasing using the increment operator
 x++
 //Getting the size of the object
 sizeof(x)

There are the Unary:

 //Positive
 +x
 //Negative
 -x
 //Not
 !x
 //Increment
 ++x
 //Decrement
 --x

There are the multiplicative:

 //Multiply
 x*y
 //Divide
 x/y
 //Mod
 x%y

Additive:

 //Addition
 x + y
 //Subtraction
 x - y

Shift:

 //Right Shift
 x >> y
 //Left Shift
 x << y

Relation:

 //Larger Than
 x > y
 //Smaller Than
 x < y
 //With equals
 x >= y
 x <= y
 //Type checking
 x is y

Equality:

 //Are Equal
 x == y
 //Are Not Equal
 x != y

Logical:

 //And
 x & y
 //Or
 x | y
 //XOr
 x ^ y

Conditional:

 //And
 x && y
 //Or
 x || y

Assignment:

 //Assign to
 x = y
 //Add do
 x += y
 //Subtract from
 x -= y
 //Multiply py
 x *= y
 //Divide by
 x /= y
 //lots more

All of this information can be found here and although it's a C# reference, UnityScript has most of the basic operators too.

Now lets look at the line where your error occurs and lets see which operator you are using:

 rollUnderToWin == winChance;
  
 if (winChance == 50.0){

So the first line you are doing a comparison between rollUnderToWin and winChance and then later you do a comparison between winChance and 50.0 to check if they are equal. Why are you doing a comparison in the first one? Does that make any sense?

Lets look at what happens when we use a single =:

 rollUnderToWin = winChance;
  
 if (winChance = 50.0){

First we assign winChance to rollUnderToWin and then we check, we assign (WTF) winChance the value of 50.0... That doesn't make any sense does it?

I think from this you should be able to figure out what you need to do to make it work.

Hope this helps,
Benproductions1