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
We will explore such "mixed" operations in a later chapter.
A common programming task is to update the value of a variable in reference to itself.
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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.
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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.