Javascript: How to retrieve the number of decimals of a *string* number?

by 
function decimalPlaces(num) {
  var match = (''+num).match(/(?:\.(\d+))?(?:[eE]([+-]?\d+))?$/);
  if (!match) { return 0; }
  return Math.max(
       0,
       // Number of digits right of decimal point.
       (match[1] ? match[1].length : 0)
       // Adjust for scientific notation.
       - (match[2] ? +match[2] : 0));
}

The extra complexity is to handle scientific notation so

decimalPlaces('.05')
2
decimalPlaces('.5')
1
decimalPlaces('1')
0
decimalPlaces('25e-100')
100
decimalPlaces('2.5e-99')
100
decimalPlaces('.5e1')
0
decimalPlaces('.25e1')
1

More Related Contents:

  1. Evaluating a string as a mathematical expression in JavaScript
  2. How can I extract a number from a string in JavaScript?
  3. Why does JavaScript handle the plus and minus operators between strings and numbers differently?
  4. What’s the best way to convert a number to a string in JavaScript?
  5. Javascript Thousand Separator / string format [duplicate]
  6. Check whether an input string contains a number in javascript
  7. JavaScript string and number conversion
  8. Get decimal portion of a number with JavaScript
  9. How to convert a String containing Scientific Notation to correct Javascript number format
  10. How can val() return Number?
  11. JavaScript adding a string to a number
  12. Regex in JavaScript for validating decimal numbers
  13. Count the recurrence of a word
  14. How to sort an array of integers correctly
  15. How to check if a string contains text from an array of substrings in JavaScript?
  16. How to remove text from a string?
  17. How to replace all dots in a string using JavaScript
  18. Check if string contains only digits
  19. Shorten string without cutting words in JavaScript
  20. How can I insert a character after every n characters in javascript?
  21. How can I remove a character from a string using JavaScript?
  22. Remove characters from a string [duplicate]
  23. is the + operator less performant than StringBuffer.append()
  24. How to extract base URL from a string in JavaScript?
  25. How to convert text to binary code in JavaScript?
  26. Split a string based on multiple delimiters
  27. How to trim() white spaces from a string?
  28. Find difference between two strings in JavaScript
  29. Javascript – Replacing the escape character in a string literal
  30. Negative numbers to binary string in JavaScript

Leave a Comment