Convert Fraction String to Decimal?

Question

Since no one has mentioned it yet there is a quick and dirty solution:

var decimal = eval(fraction); 

Which has the perks of correctly evaluating all sorts of mathematical strings.

eval("3/2")    // 1.5
eval("6")      // 6
eval("6.5/.5") // 13, works with decimals (floats)
eval("12 + 3") // 15, you can add subtract and multiply too

People here will be quick to mention the dangers of using a raw eval but I submit this as the lazy mans answer.

Here is the bare bones minimal code needed to do this:

var a = "3/2";
var split = a.split('/');
var result = parseInt(split[0], 10) / parseInt(split[1], 10);
alert(result); // alerts 1.5

JsFiddle: http://jsfiddle.net/XS4VE/

Things to consider:

• division by zero
• if the user gives you an integer instead of a fraction, or any other invalid input
• rounding issues (like 1/3 for example)

Something like this:

bits = fraction.split("/");
return parseInt(bits[0],10)/parseInt(bits[1],10);

I created a nice function to do just that, everything was based off of this question and answers but it will take the string and output the decimal value but will also output whole numbers as well with out errors

https://gist.github.com/drifterz28/6971440

function toDeci(fraction) {
    fraction = fraction.toString();
    var result,wholeNum=0, frac, deci=0;
    if(fraction.search('/') >=0){
        if(fraction.search('-') >=0){
            wholeNum = fraction.split('-');
            frac = wholeNum[1];
            wholeNum = parseInt(wholeNum,10);
        }else{
            frac = fraction;
        }
        if(fraction.search('/') >=0){
            frac =  frac.split('/');
            deci = parseInt(frac[0], 10) / parseInt(frac[1], 10);
        }
        result = wholeNum+deci;
    }else{
        result = fraction
    }
    return result;
}

/* Testing values / examples */
console.log('1 ',toDeci("1-7/16"));
console.log('2 ',toDeci("5/8"));
console.log('3 ',toDeci("3-3/16"));
console.log('4 ',toDeci("12"));
console.log('5 ',toDeci("12.2"));

I have a function I use to handle integers, mixed fractions (including unicode vulgar fraction characters), and decimals. Probably needs some polishing but it works for my purpose (recipe ingredient list parsing).

• NPM
• GitHub

Inputs "2 1/2", "2½", "2 ½", and "2.5" will all return 2.5. Examples:

var numQty = require("numeric-quantity");

numQty("1 1/4") === 1.25;  // true
numQty("3 / 4") === 0.75;  // true
numQty("¼" ) === 0.25;     // true
numQty("2½") === 2.5;      // true
numQty("¾") === 0.75;      // true
numQty("⅓") === 0.333;     // true
numQty("⅔") === 0.667;     // true

One thing it doesn't handle is decimals within the fraction, e.g. "2.5 / 5".