Javascript: Javascript Programming For Beginners Guide To Javascript Coding, Javascript Programs And Javascript Language by Josh Thompsons

Author:Josh Thompsons
Language: eng
Format: azw3, epub, pdf
Published: 2017-06-12T07:00:00+00:00

We have already covered comparison operators and of conditional statements in earlier sections but, just as a refresher, here are a few examples:

OperatorDescriptionExample

==equal toif (day == "Tuesday")

>greater thanif (earnings > 9000)

<less thanif (age < 18)

Boolean values of expressions are fundamental to conditions and comparisons in JavaScript.

Everything That has a "Real" Value is True

Examples

95

3.14

-17

"Good Day"

"false"

6 + 3 + 3.14

4 < 7

Everything That Doesn’t Have a "Real" is False

0 evaluates false in Boolean:

var x = 0;

Boolean(x); // returns false

As does the value of -0:

var x = -0;

Boolean(x); // returns false

And the value of “”, which is an empty string:

var x = "";

Boolean(x); // returns false

Also false is the value of undefined:

var x;

Boolean(x); // returns false

And the value of null:

var x = null;

Boolean(x); // returns false

As is the value of false:

var x = false;

Boolean(x); // returns false

And the value of NaN:

var x = 10 / "H";

Boolean(x); // returns false

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