index (x, s)
The index(x, s) function searches for the first occurrence of the string s in x.
It returns the index of the first character of the occurrence or 0 if the string s did not occur in x.
The search is case-insensitive.
This function returns a value of type Number.
Examples
index ("abcdabcd", "cd");
Result: 3.
index ("AbCdAbcd", "cd");
Result: 3. Note that the search is case-insensitive.