Check if the value is a string and contains a floating point number; if so, parse and format the float

Question

Check if the value is a string and contains a floating point number; if so, parse and format the float

I need to work on formatting decimal values returned by an API that only responds with strings. The requirement is to add a leading zero but no trailing zeros to any decimal value in the string. If the value is not a float, it should remain unchanged.

For example, if the input is ".7", ".70", or "0.70", my function should always return "0.7". Similarly, for inputs like "1+", it should just return "1+".

Initially, I had assumed that the API was sending floats, so I used the following approach considering the number of decimal places required as a parameter:

function setDecimalPlace(input, places) {
    if (isNaN(input)) return input;
    var factor = "1" + Array(+(places > 0 && places + 1)).join("0");

    return Math.round(input * factor) / factor;
};

How can I modify the above function to achieve the same result when the input is a decimal string, while returning the original value if it's not a float? Additionally, I am working with Angular and plan to convert this into a filter.

javascript angularjs

Answer 1

Answer №1

UPDATE #2

Additionally sourced from

function checkInteger(n) {
   return n % 1 === 0;
}

At the end, you can verify if it's a Float, then an Int, and eventually conclude that it's a String.

Referencing your comment on '7.0':

var value = '7.0';
var formattedValue = (isFloat(value) || isInt(parseFloat(value))) ? parseFloat(value) : value;

UPDATE

Actually, there's no necessity for the numberFormat function:

var value = '.7';
if(isFloat(value)) var formattedValue = parseFloat(value);

Utilize these functions:

function isFloat(num) {
  num = parseFloat(num);
  // obtained from https://stackoverflow.com/a/3886106/4640499
  return num === Number(num) && num % 1 !== 0;
}
function numberFormat(e, t, n, o) {
  // sourced from http://phpjs.org/functions/number_format/
  var r = e,
    u = isNaN(t = Math.abs(t)) ? 2 : t,
    c = void 0 == n ? '.' : n,
    a = void 0 == o ? ',' : o,
    l = 0 > r ? '-' : '',
    d = parseInt(r = Math.abs(+r || 0).toFixed(u)) + '',
    s = (s = d.length) > 3 ? s % 3 : 0
  ;
  return l + (s ? d.substr(0, s) + a : '') +
    d.substr(s).replace(/(\d{3})(?=\d)/g, '$1' + a) +
    (u ? c + Math.abs(r - d).toFixed(u).slice(2) : '');
}
function formatFloat(e) {
  return numberFormat(e, 1);
}

Then:

var value = '.7';
console.info(isFloat(value));
console.info(formatFloat(value));

if(isFloat(value)) formatFloat(value);

Answer 2

UPDATE #2

Additionally sourced from

function checkInteger(n) {
   return n % 1 === 0;
}

At the end, you can verify if it's a Float, then an Int, and eventually conclude that it's a String.

Referencing your comment on '7.0':

var value = '7.0';
var formattedValue = (isFloat(value) || isInt(parseFloat(value))) ? parseFloat(value) : value;

UPDATE

Actually, there's no necessity for the numberFormat function:

var value = '.7';
if(isFloat(value)) var formattedValue = parseFloat(value);

Utilize these functions:

function isFloat(num) {
  num = parseFloat(num);
  // obtained from https://stackoverflow.com/a/3886106/4640499
  return num === Number(num) && num % 1 !== 0;
}
function numberFormat(e, t, n, o) {
  // sourced from http://phpjs.org/functions/number_format/
  var r = e,
    u = isNaN(t = Math.abs(t)) ? 2 : t,
    c = void 0 == n ? '.' : n,
    a = void 0 == o ? ',' : o,
    l = 0 > r ? '-' : '',
    d = parseInt(r = Math.abs(+r || 0).toFixed(u)) + '',
    s = (s = d.length) > 3 ? s % 3 : 0
  ;
  return l + (s ? d.substr(0, s) + a : '') +
    d.substr(s).replace(/(\d{3})(?=\d)/g, '$1' + a) +
    (u ? c + Math.abs(r - d).toFixed(u).slice(2) : '');
}
function formatFloat(e) {
  return numberFormat(e, 1);
}

Then:

var value = '.7';
console.info(isFloat(value));
console.info(formatFloat(value));

if(isFloat(value)) formatFloat(value);

Check if the value is a string and contains a floating point number; if so, parse and format the float

Answer №1

UPDATE #2

UPDATE

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