Question

I have a slider (input type range) that is supposed to run a function when the value is being changed. The function should then display the new value in a separate div container. After placing an alert in the function, I know that the function isn’t being called, but after googling for an hour and trying a few different methods I just can’t find the error.

Here’s the HTML part:

<input id="slide" type="range" min="1" max="100" step="1" value="10" onchange="updateSlider(this.value)">

<div id="sliderAmount"></div>

JavaScript:

// Slider
function updateSlider(slideAmount)
{
  alert("error");
  var sliderDiv = document.getElementById("sliderAmount");
  sliderDiv.innerHTML = slideAmount;
}

Answer 1

It works, you just need to make sure that the JavaScript function is defined when the element is rendered, for example:

<script>
    function updateSlider(slideAmount) {
        var sliderDiv = document.getElementById("sliderAmount");
        sliderDiv.innerHTML = slideAmount;
    }
</script>
<input id="slide" type="range" min="1" max="100" step="1" value="10" onchange="updateSlider(this.value)">
<div id="sliderAmount"></div>

See this demo: https://jsfiddle.net/Mmgxg/

A better way would be to remove the inline onchange attribute:

<input id="slide" type="range" min="1" max="100" step="1" value="10">
<div id="sliderAmount"></div>

And then add the listener in your JavaScript code:

var slide = document.getElementById('slide'),
    sliderDiv = document.getElementById("sliderAmount");

slide.onchange = function() {
    sliderDiv.innerHTML = this.value;
}

https://jsfiddle.net/PPBUJ/