Question

How do I convert “1 1/4” to 1.25?

I want to take user input and convert it to the logical numerical equivalent. I say logical because 2 R and R 2 need to be 2(has to do with measuring chiropractic adjustments). Everything worked until they needed to be able to use mixed fractions.

Is there a library for this?

The only number that does not work is “1 1/4” which is converted in error to “2.75”.

    // Sample input
    var values = ["2.5", "1 1/4", "1/4", "2 R", "R 2"];

    function l(msg) {
        console.log(msg)
    }

    function toDecimal(x) {
        if (x.indexOf('/') != -1) {
            var parts = x.split(" ")
            var decParts = parts[1].split("/")
            return parseInt(parts[0], 10) + (parseInt(decParts[0], 10) / parseInt(decParts[1], 10))
        } else {
            return x
        }
    }

    function total_it_up(values){
        var total = 0,
            value = 0

        if(values === undefined)
            return 0

        $.each(values, function(index, value){
            value = value.replace(/[^0-9./]+/g, "")
            value = eval(value)
            l(value)
            total += parseFloat(value)
        })

        return total
    }

SOLUTION

    function toDecimal(x) {
        if (x.indexOf('/') != -1) {
            var parts = x.split(" ")
            var decParts;
            if (parts.length > 1) {
                decParts = parts[1].split("/");
            }
            else {
                decParts = parts[0].split("/");
                parts[0] = 0;
            }
            return parseInt(parts[0], 10) + (parseInt(decParts[0], 10) / parseInt(decParts[1], 10))
        } else {
            return x
        }
    }


    function total_it_up(values){
        var total = 0;

        if(values === undefined)
            return 0;

        $.each(values, function(index, value){
            total += parseFloat(toDecimal($.trim(value.replace(/[^0-9./ ]+/g, ""))));
        })

        return total;
    }

Answer 1

We don’t see any call for toDecimal(), so I’m assuming the $.each loop is calling it in your original code. If that is the case, then 1 1/4 is coming up as 2.75 because the regular expression is stripping the space between 1 and 1/4, resulting in 11/4, which is 2.75. Allow spaces, but $.trim the result so that any leading or trailing spaces are removed. You also shouldn’t have to use eval().