There are many number methods available to work with number datatype.
This method is used to convert number value to string. All methods are available for all types of numbers like float, double etc
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = 45.5;
var convert = temperature.toString();
document.getElementById('demo').innerHTML=typeof convert;
</script>
</body>
</html>
This method is used to convert number value to exponential format as a string.
It takes one optional parameter for number of characters after decimal places
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = 45.5;
document.getElementById('demo').innerHTML=temperature.toExponential() + "<br />" +
temperature.toExponential(1) + "<br />" +
temperature.toExponential(4);
</script>
</body>
</html>
This method is used to convert float number value with fixed number of characters after decimal points.
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = 45.56;
document.getElementById('demo').innerHTML=temperature.toFixed(0) + "<br />" +
temperature.toFixed(1) + "<br />" +
temperature.toFixed(2) + "<br />" +
temperature.toFixed(3);
</script>
</body>
</html>
This method is returns number with given number of characters as parameter.
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = 45.56;
document.getElementById('demo').innerHTML=temperature.toPrecision(1) + "<br />" +
temperature.toPrecision(2) + "<br />" +
temperature.toPrecision(3) + "<br />" +
temperature.toPrecision(4) + "<br />" +
temperature.toPrecision(5);
</script>
</body>
</html>
toPrecision() cannot take 0 as parameter value, it throws an error “RangeError: precision 0 out of range”
This method is represent number as number value.
Generally there is no need to call this method in coding.
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = 45.56;
document.getElementById('demo').innerHTML= temperature.valueOf();
</script>
</body>
</html>
There are 3 methods that are used to convert variable to numbers.
They are
This method is used to convert a variable to number type
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var temperature = "45.5";
var bool = true;
var str = "Hello World";
document.getElementById('demo').innerHTML= Number(temperature) + '<br>' +
Number(bool) + '<br>' +
Number(str);
</script>
</body>
</html>
This method is used to convert a variable to integer i.e. whole number without decimal point
<!DOCTYPE html>
<html>
<body>
The parseInt method converts variable to whole number
<p id="demo"></p>
<script>
var temperature = "45.5";
var fahrenheit = "135 5";
var bool = true;
var str = "Hello World";
document.getElementById('demo').innerHTML= parseInt(temperature) + '<br>' +
parseInt(fahrenheit) + '<br>' +
parseInt(bool) + '<br>' +
parseInt(str);
</script>
</body>
</html>
This method is used to convert a string variable to number with or without decimal point.
<!DOCTYPE html>
<html>
<body>
The parseFloat method converts string variables to numbers
<p id="demo"></p>
<script>
var temperature = "45.5";
var fahrenheit = "135 5";
var bool = true;
var str = "Hello World";
document.getElementById('demo').innerHTML= parseFloat(temperature) + '<br>' +
parseFloat(fahrenheit) + '<br>' +
parseFloat(bool) + '<br>' +
parseFloat(str);
</script>
</body>
</html>
Below are list of properties available for Numbers
Property Description MAX_VALUE Returns the largest number possible in JavaScript MIN_VALUE Returns the smallest number possible in JavaScript NEGATIVE_INFINITY Represents negative infinity (returned on overflow) NaN Represents a "Not-a-Number" value POSITIVE_INFINITY Represents infinity (returned on overflow)
All above properties are available with Number only. It will not work with number variables
<!DOCTYPE html>
<html>
<body>
The parseFloat method converts string variables to numbers
<p id="demo"></p>
<script>
document.getElementById('demo').innerHTML = Number.MAX_VALUE + '<br>' +
Number.MIN_VALUE + '<br>' +
Number.NEGATIVE_INFINITY + '<br>' +
Number.NaN + '<br>' +
Number.POSITIVE_INFINITY;
</script>
</body>
</html>