Why is angular.isNumber() not working as expected?

Question

It appears as if AngularJS\'s angular.isNumber is not working. It doesn\'t work with strings that are numbers. Am I doing something wrong? Should I just use

Answer 1

In JavaScript, typeof NaN === 'number'.

If you need to recognise a String as a Number, cast it to Number, convert back to String and compare this against the input, for example.

function stringIsNumber(s) {
    var x = +s; // made cast obvious for demonstration
    return x.toString() === s;
}

stringIsNumber('95.55'); // true
stringIsNumber('foo'); // false
// still have
stringIsNumber('NaN'); // true

Answer 2

I was working on the same problem and I was trying to work around that edge case. So I created a slightly different approach.

FIDDLE

function isStringNumber(str) {
  var parsed = parseFloat(str);
  var casted = +str;
  return parsed === casted  && !isNaN(parsed) && !isNaN(casted);
}

Answer 3

Use it as below,

angular.isNumber(eval('99.55'))

for other expressions also we may use eval(input).

Note: eval() is a javascript method

Edit: It is not recommended to use eval(), as document says Never use eval()!

Thanks @Diogo Kollross