Format a number : Number Data Type « Language Basics « JavaScript DHTML






Format a number

 

<!-- 
     Example File From "JavaScript and DHTML Cookbook"
     Published by O'Reilly & Associates
     Copyright 2003 Danny Goodman
-->

function formatNumber (num, decplaces) {
    // convert in case it arrives as a string value
    num = parseFloat(num);
    // make sure it passes conversion
    if (!isNaN(num)) {
        // multiply value by 10 to the decplaces power;
        // round the result to the nearest integer;
        // convert the result to a string
        var str = "" + Math.round (eval(num) * Math.pow(10,decplaces));
        // exponent means value is too big or small for this routine
        if (str.indexOf("e") != -1) {
            return "Out of Range";
        }
        // if needed for small values, pad zeros
        // to the left of the number
        while (str.length <= decplaces) {
            str = "0" + str;
        }
        // calculate decimal point position
        var decpoint = str.length - decplaces;
        // assemble final result from: (a) the string up to the position of
        // the decimal point; (b) the decimal point; and (c) the balance
        // of the string. Return finished product.
        return str.substring(0,decpoint) + "." + str.substring(decpoint,str.length);
    } else {
        return "NaN";
    }
}

document.myForm.total.value = formatNumber(someNumber, 2);

           
         
  








Related examples in the same category

1.Define variables, assign values and output
2.Dividing by Zero
3.Add Four Numbers from an HTML Form (and Display the Results)
4.Add characters
5.Complex class to represent complex numbers
6.A Function That Returns the Sum of Three Numbers (Stripped-Down Version)
7. Concatenating Variables and Displaying the Value Contained
8.JavaScript Loan Calculator
9.Factorials
10.Converting a Number to a String
11.Creating Number Objects Rather than Performing String-to-Number Conversions
12.Using toString() with Radix Values
13.Using JavaScript Integers
14.Conversion of Logical Values to Numeric Values
15.Using Floating-Point Numbers
16.Automatic Conversion between Types
17.Explicit Conversion Functions
18.Date Object Calculations
19.Operator Precedence and Different Data Types
20.Converting Base 10 to Base 16 Using Bitwise Operators
21.Number Calculation
22.Format a number 2
23.Decimal to 2 Hex
24.Concatenate integer variable to a string variable