The d3.descending() function in D3.js is a comparator function for the reverse natural order and returns -1 if it takes two parameters in descending order, 1 if it takes two parameters in ascending order and 0 if it takes two equal parameters.
Syntax:
d3.descending(a, b)
Parameters: This function accepts parameters a, b which are any two value.
Return Value: It returns -1 if it takes two parameters in descending order (1st parameter is greater than 2nd parameter) or 1 if it takes two parameters in ascending order (2nd parameter is greater than 1st parameter) or 0 if it takes two equal parameters.
Below programs illustrate the d3.descending() function in D3.js.
Example 1:
<!DOCTYPE html> <html>   <head>     <title>d3.descending() function</title>   </head>   <body>     <script>                   // Calling to d3.descending() function with         // two integer value parameters         A = d3.descending(50, 20);         B = d3.descending(2, 5);         C = d3.descending(5, 5);                    // Getting the results         document.write(A + "<br>");         document.write(B + "<br>");         document.write(C + "<br>");         console.log(A);     </script> </body>   </html>                    |
Output:
-1 1 0
Example 2:
<!DOCTYPE html> <html>   <head>     <title>d3.descending() function</title>   </head>   <body>     <script>                   // Calling to d3.descending() function with         // some alphabetical parameters         A = d3.descending();         B = d3.descending("a", "b");         C = d3.descending("b", "a");         D = d3.descending("b", "b");         E = d3.descending("b");                    // Getting the results         document.write(A + "<br>");         document.write(B + "<br>");         document.write(C + "<br>");         document.write(D + "<br>");         document.write(E + "<br>");     </script> </body>   </html>                    |
Output:
NaN 1 -1 0 NaN
NOTE: If this function takes alphabets as the parameter, it considers them in ascii form and evaluates the result accordingly and if the given parameter does not match the format of its parameter then it returns NaN i.e, Not a Number.
Reference: https://devdocs.io/d3~5/d3-array#descending
