Javascript sort() array of mixed data type

Question

If I have an array like:

["23", "765", "sfasf", "2.3E-3", "2.3cE-3"]

How can I order it so numbers(decimals, floats or scientific notation) are ordered ascending and after those strings that aren't numbers(for example "sfasf" or "2.3cE-3")?

Expected order of the example array:

["2.3E-3", "23", "765", "2.3cE-3", "sfasf"]

The order of the strings that can't be converted to numbers doesn't matter, they just must be at the end.

Solution from answer:

 $scope.cleanAndOrder = function(dbo, fieldName) {
    var textareaId = "textarea"+"_"+fieldName ;
    var textarea= document.getElementById(textareaId);

    //(+b && (+a!=a)) : return true (converted to 1) if b is a number and a isn't
    //(a-b) : then compare the numbers if the first comparaison isn't enough
    textarea.value = dbo.attributes[fieldName].sort(function(a,b){ return (+b && !+a) || (a-b) }).join("\n");
    var lines = textarea.value.split("\n");
    textarea.setAttribute('rows', lines.length +2);
 }

Answer 1

You can do

var arr = arr.sort(function(a,b){ return ((+b==b) && (+a!=a)) || (a-b) })

The idea is to make two comparisons:

• (+b==b) && (+a!=a) : return true (converted to 1) if b is a number and a isn't
• a-b : then compare the numbers if the first comparaison isn't enough

More in depth : +a converts a to a number. It is equal (for ==, not for ===) to a when and only when +a is a number (remember, NaN isn't equal to NaN).

Answer 2

sort function accept a function comparaison as parameter.

Define your

function compareFct(a, b) {
    if (isNaN(a)) {
        if (isNaN(b)) {  // a and b are strings
            return a.localeCompare(b);
        } else {         // a string and b number
            return 1;  // a > b
        }
    } else {
        if (isNaN(b)) {  // a number and b string
            return -1;  // a < b
        } else {         // a and b are numbers
            return parseFloat(a) - parseFloat(b);
        }
    }
}

and use it like

yourArray.sort(compareFct);