There are a few things wrong.
First,
value = G10;
needs to be in quotes if G10 is really a string
value = "G10";
Otherwise the compiler will think it an undeclared variable.
Next, this is a boolean true / false
if(value)
should be a string check
if(value != null)
Next,
x = value;
That is a value of an Object to a String.
Could be
x.value = value;
And last,
if ( x < G10)
this is incorrect because the less than sign wont work
with strings unless the are a numeric value and using parseFloat or parsInt to compare them
This would be in the ball park.
if ( x.value != "G10")
or if both values were numeric you could use
if ( parseFloat(x.value) < 10)
HTH