[JavaScript] Use `+` opertor to add one string and one number
The rule is: If you add a number and a string, the result will be a string!
Example
x=5+5;
y="5"+5;
z="Hello"+5;
y="5"+5;
z="Hello"+5;
The result of x,y, and z will be:
10
55
Hello5
55
Hello5