A.3. Operators

An operator performs some computation on one or more variables. Operators can be classified as assignment, comparison, conditional, boolean, arithmetic, string, bitwise, and special. These operators are summarized in Table A-3

Table A-3. ECMAScript operators
OperatorsDescriptionExamples
assignment = += -= *= /= %= <<= >>= >>>= &= ^= |= These operators assign a value to a variable. 
x = 3; 
y = fibonacci(10);
x = "Hello."
x = y;
x += y  // fills x with x + y
x *= y  // fills x with x * y

comparison == != > >= < <= These operators represent a relation between two expressions, evaluate to a boolean. 
x <= 10
5 != 4  // always evaluates 
        // to true

conditional ? :This operator is a shorthand for if-then-else logic. 
y = (x < 0) ?  0 : x;
// If x is less than 0 
// then evaluate to 0, 
// otherwise evaluate to x

boolean && || !With boolean values, these operators represent logical and, logical or, and logical not. 
if(p && ! (q || r )){
   r = false;
}
// If p and not (q or r) 
// then let r = false.

arithmetic + - * / %With numbers, these operators perform basic arithetic. 
var x = 5 + 4;
var y = x % 3;
// "%" represents modulo.

string + += ==These operators compare and concatenate strings. 
var s = "hello " + 2 
        + " the world.";
if(s == "hello 2 the world"){
   s += "!!";
}

bitwise & | ^ << >> >>>These operators treat numbers as bit fields. 
var x = 1 | 4 >> 3;

special [typeof . functionThese operators manage language constructs such as membership, type resolution, and function resolution. 
var a = Employee.FirstName;
if (o typeof Employee){
   o.FirstName = "John";
}


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