|| and && Are Not “Logical Operators” In JavaScript

|| and && Are Not “Logical Operators” In JavaScript

A more apt name would be “selector operators.”

Hear me out.

If you’ve written software with PHP or any statically typed language, you’d know that the value of any expression including either || or && will return a boolean.

Enter JavaScript.

The name logical operators doesn’t completely describe the function of || and && in JavaScript. A more apt name would be selector operators.

This is because, in JavaScript, || or && will return one (and only one) of the two expression values rather than a boolean value.

Quoting the ES5 spec from section 11.11

The value produced by a && or || operator is not necessarily of type Boolean. The value produced will always be the value of one the two operand expressions.

Consider the following:

var a = 10;
var b = "foo"
var c = null;

a || b  // 10
a && b  // "foo"

c || b  // "foo"
c && b  // null

javascript coding

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