Function is undefined, but i had defined it

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I'm a PLC programmer, i made a html page and i need it script refresh every second, so in my body i placed:

    <body onload="changeimage()">

.... code ....

</body>

And the script:

<script>
setInterval(function changeimage() {
var sonde = ["Sonda1","Sonda2","Sonda3","Sonda4"];
var tsonde = ["tsonda1","tsonda2","tsonda3","tsonda4"];
var temperature = [:="OUTPUT".AlarmTemp.Sonda1:,:="OUTPUT".AlarmTemp.Sonda2:,:="OUTPUT".AlarmTemp.Sonda3:,:="OUTPUT".AlarmTemp.Sonda4:];
var hotcold = document.getElementById("Fiocco");
if (:="OUTPUT".Stagione.Estate: > 0){
      hotcold.src="sun.jpg"}
if (:="OUTPUT".Stagione.Inverno: > 0){
      hotcold.src="Neve.png"}    
 for (x in temperature) {
           var icona = document.getElementById(sonde[x]);
                     if (temperature[x] > 0 ){
               icona.src="Paverde.png"
           }
           else{
               icona.src="Parossa.png"
           }

     }
}, 1000);   
</script>

Anyway i get the error: ReferenceError: changeimage is not defined

P.S.: Don't get fooled by the arrays who start with ":", is a PLC syntax, is correct.

@ Even removing the setinterval option, the script is not working.

Define the function first and make sure the script is loaded.

Example in code pen: https://codepen.io/mikila85/pen/NWPvQPE

function changeimage() {
    setInterval(function() {
        var sonde = ["Sonda1","Sonda2","Sonda3","Sonda4"];
        var tsonde = ["tsonda1","tsonda2","tsonda3","tsonda4"];
        var temperature = [:="OUTPUT".AlarmTemp.Sonda1:,:="OUTPUT".AlarmTemp.Sonda2:,:="OUTPUT".AlarmTemp.Sonda3:,:="OUTPUT".AlarmTemp.Sonda4:];
        var hotcold = document.getElementById("Fiocco");

        if (:="OUTPUT".Stagione.Estate: > 0){
            hotcold.src="sun.jpg"
        }
        if (:="OUTPUT".Stagione.Inverno: > 0){
            hotcold.src="Neve.png"
        }

        for (x in temperature) {
            var icona = document.getElementById(sonde[x]);
            if (temperature[x] > 0 ){
                icona.src="Paverde.png"
            }
            else{
                icona.src="Parossa.png"
            }

        }
    }, 1000);
}

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Anyway i get the error: ReferenceError: changeimage is not defined

setInterval(function changeimage() {

Sure it won't be defined, as it was only defined as a callback function to the setInterval() call.

So it won't be visible outside of this setInterval scope, and it won't be visible for the onload event listener of your body.

Solution:

You should define your changeimage() function in the global scope (outside of the setInterval like this:

<head>
  <script>
    function changeimage() {
      var sonde = ["Sonda1", "Sonda2", "Sonda3", "Sonda4"];
      var tsonde = ["tsonda1", "tsonda2", "tsonda3", "tsonda4"];
      var temperature = [: = "OUTPUT".AlarmTemp.Sonda1: ,: = "OUTPUT".AlarmTemp.Sonda2: ,: = "OUTPUT".AlarmTemp.Sonda3: ,: = "OUTPUT".AlarmTemp.Sonda4: ];
      var hotcold = document.getElementById("Fiocco");
      if (: = "OUTPUT".Stagione.Estate: > 0) {
        hotcold.src = "sun.jpg"
      }
      if (: = "OUTPUT".Stagione.Inverno: > 0) {
        hotcold.src = "Neve.png"
      }
      for (x in temperature) {
        var icona = document.getElementById(sonde[x]);
        if (temperature[x] > 0) {
          icona.src = "Paverde.png"
        } else {
          icona.src = "Parossa.png"
        }

      }
    }


    setInterval(changeimage(), 1000);
  </script>
</head>

<body onload="changeimage()">

  .... code ....

</body>

undefined, A function returns undefined if a value was not returned . You can use undefined and the strict equality and inequality operators to determine before if (y === void 0) { // throws Uncaught ReferenceError: y is not defined }� Checks whether the given constant exists and is defined. Note: . If you want to see if a variable exists, use isset() as defined() only applies to constants.If you want to see if a function exists, use function_exists().

try this

function changeImage(){
  ....
}

// if you need to call every 1 sec
setInterval(changeImage,1000);

// else
changeImage();  or // setTimeout(changeImage,1000)

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The 10 Most Common Mistakes JavaScript Developers Make, As JavaScript coding techniques and design patterns have become increasingly Uncaught TypeError: undefined is not a function If both functions defined inside replaceThing actually used priorThing , it would be important that they both � In TypeScript 3.7 we have now Optional chaining and Nullish Coalescing to check null and undefined in the same time, example:. let x = foo?.bar.baz(); this code will check if foo is defined otherwise it will return undefined

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Why do I get the error "Undefined function or variable"?, Learn more about undefined, function, variable, error MATLAB. of MATLAB try to resolve these typos with “Did you mean” suggestions. In later versions of MATLAB, this is not an “Undefined function or variable” error, and MATLAB lets you� '*****' is undefined if function is already present . Something like the image i posted . For to solve this issue you need to give permission to the folder in web.config for access by user. I did as below.

Comments
  • your changeimage function definition was inside a setInterval, that's why your page doesn't see that function once it's loaded. You might want to move that function outside setIntetval, and inside call something like setInterval( changeimage, 1000)
  • body onload="..." searches the specified function from the global scope only. The function you've defined is a named function expression passed as an argument to setInterval method. That argument is not visible to the global scope.
  • @DaniloCervellini Hi, I Edit your code (above to work) and also put codepen example for simple use.
  • Was two problems, one is that you solved, the other is that it works only with the PLC connected (Due the ":" issue). Loading it without plc gave the same problem. Now i have a new one about image refresh but i'm looking for solutions
  • Good luck i happy that i could help.
  • I have the same problem even if i dont put any setInterval