toFixed() doesn't seem to work... why?

[espruino-discuss]

Posted at 2014-06-18 by d0773d

Life happened so I put my project to the side for a couple of months. I decided to pick the project back up today and updated the firmware on the Espruino. By the way I really like the new GUI of the IDE :-)

The issue I am having is toFixed(2) doesn't seem to get the decimal place to only two decimal places. toFixed(2) seemed to work before I took a break from my project.

I hit the Send to Espruino button. I get the following output.

_____ _ | |_ ___ ___ _ ||___ ___ | |
-| . | _| | | | | . | ||| || |||||_|
|| http://espruino.com 1v64 Copyright 2014 G.Williams

echo(0);
80.66461538461538793853833340108394622802734375 0
161.403076923076923776534385979175567626953125 1
241.99384615384616381561500020325183868408203125 2
322.7323076923076996536110527813434600830078125 3
403.54461538461538339106482453644275665283203125 4
484.209230769230771329603157937526702880859375 5
564.83362900747715684701688587665557861328125 6
645.49824439209260162897408008575439453125 7
726.0890136228617848246358335018157958984375 8
806.62281160369502686080522835254669189453125 9 Temp: 80.662281160369502686080522835254669189453125
=undefined

CODE:

function onInit() {

  function getResTempValue(x) {
    var temp=0;
    var avgTemp=0;
    for (var i=0;i<x;i++)
    {
      var vOut = E.getAnalogVRef() * analogRead(A0); // if you attached VOUT to Ao
      var vZero = 0.4;
      var tCoeff =  19.5 / 1000;
      var tempinc = (vOut - vZero) / tCoeff;
      var tempinf = tempinc * (9 / 5) + 32;
      temp = temp + tempinf;
      console.log(temp);
      console.log(i);
    }
    temp = temp / x;
    temp.toFixed(2);  //<-- Doesn't seem to work.

    console.log("Temp: " + temp);
    return temp;
  }

  getResTempValue(10);
}

onInit();

[espruino-discuss]

Posted at 2014-06-18 by DrAzzy

Number.toFixed() returns a string with the specified format.

What you would want to do is:

var tfixed = temp.toFixed(2);  
    console.log("Temp: " + tfixed);
    return temp; //we probably want to return the number, not a string

or

    console.log("Temp: " + temp.toFixed(2));
    return temp;

[gfwilliams]

Posted at 2014-06-18 by @gfwilliams

Thanks @drazzy

As far as I'm aware that's never worked, so I'm not quite sure why everything was fine for you before!

[espruino-discuss]

Posted at 2014-06-19 by d0773d

DrAzzy, thanks for your help. Gordon, your right the code never worked. Which explains why I was getting erratic values from my sensor readings. Now, my sensor readings are stable.

[espruino-discuss]

Posted at 2014-07-05 by d0773d

Code that works:

function onInit() {
  var cmd="";
  Serial1.setup(9600/*baud*/);
  Serial1.onData(function (e) {
    console.log("RX Data: " + e.data);
  });

  function getResTempValue(x) {
    var temp=0;
    var avgTemp=0;
    var tfixed=0;

    for (var i=0;i<x;i++)
    {
      var vOut = E.getAnalogVRef() * analogRead(A0); // if you attached VOUT to Ao
      var vZero = 0.4;
      var tCoeff =  19.5 / 1000;
      var tempinc = (vOut - vZero) / tCoeff;
      var tempinf = tempinc * (9 / 5) + 32;
      temp = temp + tempinf;
      console.log(temp);
      console.log(i);
    }
    temp = temp / x;
    tfixed = temp.toFixed(2);

    console.log("Temp: " + tfixed);
    return temp;
  }

  getResTempValue(10);
}

onInit();