Javascript IndexOf with integers in string not working

Question

Can anyone tell me why does this not work for integers but works for characters? I really hate reg expressions since they are cryptic but will if I have too. Also I want to include the "-()" as well in the valid characters.

String.prototype.Contains = function (str) {  
    return this.indexOf(str) != -1;
};

var validChars = '0123456789';               

var str = $("#textbox1").val().toString();
if (str.Contains(validChars)) {
    alert("found");
} else {
    alert("not found");
}

Answer 1

Review

String.prototype.Contains = function (str) {  
    return this.indexOf(str) != -1;
};

This String "method" returns true if str is contained within itself, e.g. 'hello world'.indexOf('world') != -1would returntrue`.

var validChars = '0123456789';               

var str = $("#textbox1").val().toString();

The value of $('#textbox1').val() is already a string, so the .toString() isn't necessary here.

if (str.Contains(validChars)) {
    alert("found");
} else {
    alert("not found");
}

This is where it goes wrong; effectively, this executes '1234'.indexOf('0123456789') != -1; it will almost always return false unless you have a huge number like 10123456789.

What you could have done is test each character in str whether they're contained inside '0123456789', e.g. '0123456789'.indexOf(c) != -1 where c is a character in str. It can be done a lot easier though.

Solution

I know you don't like regular expressions, but they're pretty useful in these cases:

if ($("#textbox1").val().match(/^[0-9()]+$/)) {
   alert("valid");
} else {
   alert("not valid");
}

Explanation

[0-9()] is a character class, comprising the range 0-9 which is short for 0123456789 and the parentheses ().

[0-9()]+ matches at least one character that matches the above character class.

^[0-9()]+$ matches strings for which ALL characters match the character class; ^ and $ match the beginning and end of the string, respectively.

In the end, the whole expression is padded on both sides with /, which is the regular expression delimiter. It's short for new RegExp('^[0-9()]+$').

Answer 2

Assuming you are looking for a function to validate your input, considering a validChars parameter:

String.prototype.validate = function (validChars) {  
    var mychar;
    for(var i=0; i < this.length; i++) {
        if(validChars.indexOf(this[i]) == -1) { // Loop through all characters of your string.
            return false; // Return false if the current character is not found in 'validChars' string.
        }
    }
    return true;
};

var validChars = '0123456789';

var str = $("#textbox1").val().toString();
if (str.validate(validChars)) {
    alert("Only valid characters were found! String validates!");
} else {
    alert("Invalid Char found! String doesn't validate.");
}

However, This is quite a load of code for a string validation. I'd recommend looking into regexes, instead. (Jack's got a nice answer up here)

Answer 3

You are passing the entire list of validChars to indexOf(). You need to loop through the characters and check them one-by-one.

Demo

String.prototype.Contains = function (str) {  

  var mychar;
  for(var i=0; i<str.length; i++)
  {
    mychar = this.substr(i, 1);
    if(str.indexOf(mychar) == -1)
    {
        return false;
    }
  }

  return this.length > 0;
};

To use this on integers, you can convert the integer to a string with String(), like this:

var myint = 33; // define integer
var strTest = String(myint); // convert to string
console.log(strTest.Contains("0123456789")); // validate against chars