function changeColor() {
        var divOneElement = document.getElementById("div1");
        divOneElement.className = "fuschiaback";
       
    }
You can further manipulate an HTML element by accessing the text.  Add another button as follows:
<input type = "button" value = "Change Text" onclick = "changeText()">
You will now define the function changeText()
function changeText() {
       //Add your code below
        var divTwoElement = document.getElementById("div2");
        divTwoElement.innerHTML = "Changed with a Button!";
       
    }
<canvas id = "canvas">
   
   
</canvas>
We will add the following components:
<input type="button" value="Lime Background" onclick="doLime()">
   
<br>
   
<input type="button" value="Yellow Background" onclick="doYellow()">
<br>
<input type="button" value="Make Rectangles" onclick="makeRectangles()">
   
<br>
<input type="button" value="Say Hello" onclick="makeText()">
   
<input type="color" value="red" id="clr" onchange="doColor()">
<input type="range" min="10" max="100" value = "10" id="sldr" oninput="doSquare()">
What do the above input’s create?  We will now need to define the functions when the input is changed.  Add the following code within your script tags below:
//global variables
var canvOne = document.getElementById("canvas");
var ctx = canvOne.getContext("2d");
       
function doLime() {   
    canvOne.style.backgroundColor ="lime";
}
function doYellow() {   
    //Add code so that the background becomes yellow
}
   
function makeRectangles() {   
    ctx.fillStyle = "blue";
    ctx.fillRect(10, 10, 40, 40);
}
   
function makeText() {
     ctx.fillStyle="black";
     ctx.font = "30px Arial";
     ctx.fillText("Hello", 10, 80);
    }
   
function doColor() {
     var colorinput = document.getElementById("clr");
     var color = colorinput.value;
     canvOne.style.backgroundColor = color;
       
    }
   
function doSquare() {
     var sliderInput = document.getElementById("sldr");
     var value = sliderInput.value;
     //larger will ovewrite smaller, so need to clear
     ctx.clearRect(0, 0, canvOne.width, canvOne.height);
     ctx.fillStyle = "yellow";
     ctx.fillRect(10, 10, value, value);
       
    }