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How do I get the number of zero decimals behind the comma (but not the total)? So to illustrate an example:
0.00001 > 4
0.000015 > 4
0.0000105 > 4
0.001 > 2
I am looking for methods that are efficient (meaning that they optimize the calculation time).
1000
The first digit after the decimal represents the tenths place. The next digit after the decimal represents the hundredths place. The remaining digits continue to fill in the place values until there are no digits left.
The toFixed() method returns a string representation of numObj that does not use exponential notation and has exactly digits digits after the decimal place. The number is rounded if necessary, and the fractional part is padded with zeros if necessary so that it has the specified length.
JavaScript Number toFixed() The toFixed() method rounds the string to a specified number of decimals.
You can use logarithms to find the magnitude of the number:
var x = 0.00195;
var m = -Math.floor( Math.log(x) / Math.log(10) + 1);
document.write(m); // outputs 2
Later versions of JavaScript have Math.log10, so it would be:
var x = 0.00195;
var m = -Math.floor( Math.log10(x) + 1);
document.write(m); // outputs 2
How using the base-10 logarithm of the numbers works:
| x | Math.log10(x) | Math.floor(Math.log10(x) + 1 ) |
|---|---|---|
| 0.1 | -1 | 0 |
| 0.01 | -2 | -1 |
| 0.015 | -1.8239… | -1 |
| 0.001 | -3 | -2 |
| 0.00001 | -5 | -4 |
| 0.000015 | -4.8239… | -4 |
| 0.0000105 | -4.9788… | -4 |
106
Use a regex to match the number of zeros after a decimal point and then count them.
var zeros = float.toString().match(/(\.0*)/)[0].length - 1;
DEMO
30
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