I am receiving undefined when using charAt[i]

I am not sure why I am receiving undefined when I loop through data which is a string, To see if data contained a string I did console.log(typeof data + ": " + data); which echoed out String : 26.19. From my understanding, I thought looping through the data string and using charAt[i] I should in theory return the character at i, however, I am receiving undefined. Why is that and how do I return the character at i?

s7s.prototype.sendValue = function (data) {
  var a = this.address;
  var length = data.length;
  var i;
  var val;
  var dpLoc;

  console.log(typeof data + ": " + data); //echos out a string

  for(i=0; i<data.length; i++) {
    var char = data.charAt[i];

    console.log(data.charAt[i]);

    if(char != ".") {
      val += char;
    }

    if(char == ".") {
      dpLoc = i;
    }
  }

  //console.log(val);

  //I2C2.writeTo(a, value);
};

Using var char = data.substr(i, 1); seems to work.

Finally found it! Try data.charAt(i) instead of data.charAt[i], or simply data[i] :)

doh! I used brackets instead of parentheses. data.charAt(i); works.

Code:

s7s.prototype.sendValue = function (data) {
  var a = this.address;
  var clr = this.displayTable.Clear; //Display clear command
  var dpc = this.displayTable.dp.cmd; //Decimal point command
  var dplo = this.displayTable.dp.location; //Decimal point location map

  var i;
  var length = data.length;
  var dpLoc;
  var value = "";

  for(i=0; i<length; i++) {
    var char = data.charAt(i);

    if(char != ".") {
      value += char;
    }

    if(char == ".") {
      dpLoc = i;
    }
  }

  I2C1.writeTo(a, clr); //Clear display
  I2C1.writeTo(a, value);

  if(typeof dpLoc !== 'undefined') {
    I2C1.writeTo(a, dpc);
    I2C1.writeTo(a, dplo[dpLoc - 1]);
  }
};

Two thoughts:

if (char != ".") { value += char; }
else { dpLoc = i; }

'data' always has a decimal point?

I2C1.writeTo(a, dpc);
  if(typeof dpLoc !== 'undefined') {
    I2C1.writeTo(a, dplo[dpLoc - 1]);
  }

No, results don't always have to return in a decimal format, however, in this case they will. I have
if(typeof dpLoc !== 'undefined')
For the moments where I wont, for example, taking a PPM reading of a solution. That was my attempt to write a generic function to output a result to my 4 - digit 7 segment display.

Doh, I get it now, wasn't reading carefully enough and missed the two I2CI.writeTo()'s before the decimal point check, sorry, my bad!

If data is 1234 and there is no decimal point in the value, the display will only show 1234. I still have to add checks for how many digits and if the display comma needs to be enabled or not. For example, 25.2'C. I have an idea:
code:

if (char == "'") { 
I2C1.writeTo (a,0b00001000);  //turn on comma}

yeah, sorry, I just realized that and edited my comment, sorry :)