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JavaScript Number Methods
Number methods enables the user to work with numbers.
Number Methods and Properties
Primitive values (like 3.14 or 2014), does not have properties and methods (because they are not objects).
But with JavaScript, methods and properties are available to primitive values, as JavaScript treats primitive values as objects while executing methods and properties.
The toString() Method
The toString() method returns a number as a string.
All number methods are used on any type of numbers (literals, variables, or expressions):
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Methods</h2>
<p>The toString() method converts a number to a string.</p>
<p id=”demo”></p>
<script>
let x = 123;
document.getElementById(“demo”).innerHTML =
x.toString() + “<br>” +
(123).toString() + “<br>” +
(100 + 23).toString();
</script>
</body>
</html>
Output
JavaScript Number Methods
The toString() method converts a number to a string.
123 123 123The toExponential() Method
toExponential() returns a string, consisting of a number rounded and written using exponential notation.
A parameter specifies the number of characters behind the decimal point:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Methods</h2>
<p>The toExponential() method returns a string, with the number rounded and written using exponential notation.</p>
<p>An optional parameter defines the number of digits behind the decimal point.</p>
<p id=”demo”></p>
<script>
let x = 9.656;
document.getElementById(“demo”).innerHTML =
x.toExponential() + “<br>” +
x.toExponential(2) + “<br>” +
x.toExponential(4) + “<br>” +
x.toExponential(6);
</script>
</body>
</html>
Output
JavaScript Number Methods
The toExponential() method returns a string, with the number rounded and written using exponential notation.
An optional parameter defines the number of digits behind the decimal point.
9.656e+0 9.66e+0 9.6560e+0 9.656000e+0The toFixed() Method
toFixed() returns a string, with the number written with a specified number of decimals:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Methods</h2>
<p>The toFixed() method rounds a number to a given number of digits.</p>
<p>For working with money, toFixed(2) is perfect.</p>
<p id=”demo”></p>
<script>
let x = 9.656;
document.getElementById(“demo”).innerHTML =
x.toFixed(0) + “<br>” +
x.toFixed(2) + “<br>” +
x.toFixed(4) + “<br>” +
x.toFixed(6);
</script>
</body>
</html>
Output
JavaScript Number Methods
The toFixed() method rounds a number to a given number of digits.
For working with money, toFixed(2) is perfect.
10 9.66 9.6560 9.656000The toPrecision() Method
toPrecision() returns a string, consists of a number written with a specified length:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Methods</h2>
<p>The toPrecision() method returns a string, with a number written with a specified length:</p>
<p id=”demo”></p>
<script>
let x = 9.656;
document.getElementById(“demo”).innerHTML =
x.toPrecision() + “<br>” +
x.toPrecision(2) + “<br>” +
x.toPrecision(4) + “<br>” +
x.toPrecision(6);
</script>
</body>
</html>
Output
JavaScript Number Methods
The toPrecision() method returns a string, with a number written with a specified length:
9.656 9.7 9.656 9.65600The valueOf() Method
valueOf() returns a number as a number.
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Methods</h2>
<p>The valueOf() method returns a number as a number:</p>
<p id=”demo”></p>
<script>
let x = 123
document.getElementById(“demo”).innerHTML =
x.valueOf() + “<br>” +
(123).valueOf() + “<br>” +
(100 + 23).valueOf();
</script
</body>
</html>
Output
JavaScript Number Methods
The valueOf() method returns a number as a number:
123 123 123In JavaScript, a number can be a primitive value (typeof = number) or an object (typeof = object)
The valueOf() method is used internally in JavaScript to convert Number objects to primitive values.
There are 3 JavaScript methods that is used to convert variables to numbers:
- The Number() method.
- The parseInt() method.
- The parseFloat() method.
These methods are not number methods, but global JavaScript methods.
The Number() Method
Number() are used to convert JavaScript variables to numbers:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Global Methods</h2>
<p>The Number() method converts variables to numbers:</p>
<p id=”demo”></p>
<script>
document.getElementById(“demo”).innerHTML =
Number(true) + “<br>” +
Number(false) + “<br>” +
Number(“10”) + “<br>” +
Number(” 10″) + “<br>” +
Number(“10 “) + “<br>” +
Number(” 10 “) + “<br>” +
Number(“10.33”) + “<br>” +
Number(“10,33”) + “<br>” +
Number(“10 33”) + “<br>” +
Number(“John”);
</script>
</body>
</html>
Output
JavaScript Global Methods
The Number() method converts variables to numbers:
The Number() Method Used on Dates
Number() can also convert a date to a number.
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Global Methods</h2>
<p>The Number() method can convert a date to a number:</p>
<p id=”demo”></p>
<script>
let x = new Date(“1970-01-01”);
document.getElementById(“demo”).innerHTML = Number(x);
</script>
</body>
</html>
Output
JavaScript Global Methods
The Number() method can convert a date to a number:
The number of milliseconds between 1970-01-02 and 1970-01-01 is 86400000:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Global Methods</h2>
<p>The Number() method can convert a date to a number:</p>
<p id=”demo”></p>
<script>
let x = new Date(“1970-01-02”);
document.getElementById(“demo”).innerHTML = Number(x);
</script>
</body>
</html>
Output
JavaScript Global Methods
The Number() method can convert a date to a number:
86400000
The parseInt() Method
parseInt() parses a string and returns a whole number. Spaces are allowed. Only the first number is returned:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Global Functions</h2>
<h2>parseInt()</h2>
<p>The global JavaScript function parseInt() converts strings to numbers:</p>
<p id=”demo”></p>
<script>
document.getElementById(“demo”).innerHTML =
parseInt(“-10”) + “<br>” +
parseInt(“-10.33”) + “<br>” +
parseInt(“10”) + “<br>” +
parseInt(“10.33”) + “<br>” +
parseInt(“10 6”) + “<br>” +
parseInt(“10 years”) + “<br>” +
parseInt(“years 10”);
</script>
</body>
</html>
Output
JavaScript Global Functions
parseInt()
The global JavaScript function parseInt() converts strings to numbers:
The parseFloat() Method
parseFloat() parses a string and returns a number. Spaces are allowed. Only the first number is returned:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Global Methods</h2
<p>The parseFloat() method converts strings to numbers:</p
<p id=”demo”></p>
<script>
document.getElementById(“demo”).innerHTML =
parseFloat(“10”) + “<br>” +
parseFloat(“10.33”) + “<br>” +
parseFloat(“10 6”) + “<br>” +
parseFloat(“10 years”) + “<br>” +
parseFloat(“years 10”);
</script>
</body>
</html>
Output
JavaScript Global Methods
The parseFloat() method converts strings to numbers:
JavaScript MIN_VALUE and MAX_VALUE
MAX_VALUE returns the largest possible number in JavaScript.
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Properties</h2>
<p>MAX_VALUE returns the largest possible number in JavaScript.</p
<p id=”demo”></p>
<script>
let x = Number.MAX_VALUE;
document.getElementById(“demo”).innerHTML = x;
</script>
</body>
</html>
Output
JavaScript Number Properties
MAX_VALUE returns the largest possible number in JavaScript.
1.7976931348623157e+308
MIN_VALUE returns the lowest possible number in JavaScript.
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Properties</h2>
<p>MIN_VALUE returns the smallest number possible in JavaScript.</p>
<p id=”demo”></p>
<script>
let x = Number.MIN_VALUE;
document.getElementById(“demo”).innerHTML = x;
</script>
</body>
</html>
Output
JavaScript Number Properties
MIN_VALUE returns the smallest number possible in JavaScript.
5e-324
JavaScript POSITIVE_INFINITY
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Properties</h2>
<p>POSITIVE_INFINITY</p>
<p id=”demo”></p>
<script>
let x = Number.POSITIVE_INFINITY;
document.getElementById(“demo”).innerHTML = x;
</script>
</body>
</html>
Output
JavaScript Number Properties
POSITIVE_INFINITY
Infinity
JavaScript NEGATIVE_INFINITY
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Number Properties</h2>
<p>NEGATIVE_INFINITY</p>
<p id=”demo”></p
<script>
let x = Number.NEGATIVE_INFINITY;
document.getElementById(“demo”).innerHTML = x;
</script>
</body>
</html>
Output
JavaScript Number Properties
NEGATIVE_INFINITY
-Infinity