The String Operator
So far we have only seen operators that work on operands which are of type
number, but there are operators that work on other data types as well. In particular, the
+ operator can be used with
string operands to concatenate, or join together two strings.
"Launch" + "Code" evaluates to
+ used with numbers to
+ used with strings.
console.log(1 + 1); console.log("1" + "1");
This example demonstrates that the operator + behaves differently based on the data type of its operands.
So far we have only seen examples of operators working with data of like type. For the examples
1 + 1 and
"1" + "1", both operands are of type
It is possible, however, to mix types with an expression such as
1 + "1". The results of doing so can be unexpected, and at this stage of your coding journey we strongly advise against creating such expressions.
We will explore such “mixed” operations in a later chapter.
Compound Assignment Operators
A common programming task is to update the value of a variable in reference to itself.
let x = 1; x = x + 1; console.log(x);
Line 2 may seem odd to you at first, since it uses the value of the variable
x to update
x to be one more than its current value.”
This action is so common, in fact, that it has a shorthand operator,
+=. The following example has the same behavior as the one above.
let x = 1; x += 1; console.log(x);
x += 1 is shorthand for
x = x + 1.
There is an entire family of such shorthand operators, known as compound assignment operators.