相加运算符 (+)

相加运算符 (+) 用于对两个操作数进行相加运算，如果操作数为字符串则该运算符将两个操作数连接成一个字符串。

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

表达式: x + y

// Number + Number -> addition
1 + 2 // 3

// Boolean + Number -> addition
true + 1 // 2

// Boolean + Boolean -> addition
false + false // 0

// String + String -> concatenation
'foo' + 'bar' // "foobar"

// Number + String -> concatenation
5 + 'foo' // "5foo"

// String + Boolean -> concatenation
'foo' + false // "foofalse"

注: '+'两侧只要有一侧是字符串，另一侧的数字则会自动转换成字符串，因为其中存在隐式转换

• Subtraction operator
• Division operator
• Multiplication operator
• Remainder operator
• Exponentiation operator
• Increment operator
• Decrement operator
• Unary negation operator
• Unary plus operator