JavaScript Math Operators

المعرفة:: JavaScript
الحالة:: ملاحظة_مؤرشفة
المراجع:: JavaScript Essential Training

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Math Operators

// 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"  
  
// Subtraction with numbers  
5 - 3; // 2  
3 - 5; // -2  
  
// Number - String -> Subtraction  
15 - "4"; // 11  
  
// Subtraction with non-numbers  
"foo" - 3; // NaN  

Increment and Decrement

• If used postfix, with operator after operand (for example, x++), the increment operator increments and returns the value before incrementing.
• If used prefix, with operator before operand (for example, ++x), the increment operator increments and returns the value after incrementing.

// Prefix increment  
let a = 2;  
b = ++a;  
// a = 3  
// b = 3  
  
// Postfix increment  
let x = 3;  
y = x++;  
// y = 3  
// x = 4  
  
// Prefix decrement  
let a = 2;  
b = --a;  
  
// a = 1  
// b = 1  
  
// Postfix decrement  
let x = 3;  
y = x--;  
// y = 3  
// x = 2