parseFloat(1.51e-6);

// returns 0.00000151



parseFloat(1.23e-7);

// returns 1.23e-7

// required 0.000000123

I am sorting table columns containing a wide range of floating-point numbers, some represented in scientific notation.

I am using the jQuery tablesorter2.0 plugin which is using 'parseFloat' for cells that start with a digit.
The issue is that parseFloat returns very small numbers represented as 1.23e-7 as a string and is not expanding this to 0.000000123.
As a result tablesorter sorts the content of the column as text instead of numerics.

**Column To Sort**

2.34

1.01

13.56

1.23e-7



**After Sort Now**

1.01

1.23e-7

13.56

2.34



**Expect**

1.23e-7

1.01

2.34

13.56

Is there an efficient way of representing very small scientific notation numbers as expanded floating-point numbers?

Solution:

tablesorter determines how to sort a column based on the first of tablesorters automatic parsers to return true for the content of a cell in that column.
If the cell contained 1.23e-7 than it defaulted to sort by text because the 'digit' parser does not interpret this as a number.

So to workaround, the following code represents the scientific notation number as a string that tablesorter can interpret/parse as a digit and so ensures numerical sorting on the column. @bitplitter - thanks for the toFixed() tip.

var s = 1.23e-7;

// Handle exponential numbers.

if (s.match(/^[-+]?[1-9].[0-9]+e[-]?[1-9][0-9]*$/)) {

  s = (+s).toFixed(getPrecision(s));

}

//returns 0.000000123



// Get a nice decimal place precision for the scientific notation number.

// e.g. 1.23e-7 yields 7+2 places after the decimal point

// e.g. 4.5678e-11 yields 11+4 places after the decimal point

function getPrecision(scinum) {

  var arr = new Array();

  // Get the exponent after 'e', make it absolute.  

  arr = scinum.split('e');

  var exponent = Math.abs(arr[1]);



  // Add to it the number of digits between the '.' and the 'e'

  // to give our required precision.

  var precision = new Number(exponent);

  arr = arr[0].split('.');

  precision += arr[1].length;



  return precision;

}