Onclick function in js not working properly

Question

onclick function to change an image once clicked but its giving me an error in Js saying unexpected else please I need an assistance Im a newbie in programming

function changeImage(){
    let a=document.getElementById("changeimg").src
        if (a==="img/save.png") {
            return a = "img/saveblack.png"
        } 

}  
 else{
    return a= "img/save.png"
}

</div>
                
                <div class="wrapper_center">
                    <img src="img/profilepix.jpg">
                </div>

                <div class="wrapper_bottom">
                    <div class="reaction_wrapper">
                        <a href=""><img src="img/heart.png"></a>
                        <a href=""><img src="img/messagereaction.png"></a>
                        <a href=""><img src="img/message.png"></a>
                        <img src="img/save.png" id="changeimg" onclick="changeImage()">
                    </div>

Answer 1

Try this ( I suggest you use a good text editor lik vscode, webstorm, itellij or atom, all the syntax errors you have will be highlighted)

function changeImage(){
    let element = document.getElementById("changeimg")
    element.src = element.src ==="img/save.png" ? "img/saveblack.png" : "img/save.png";
}

<div class="wrapper_center">
<img src="img/profilepix.jpg">
</div> 
<div class="wrapper_bottom"> 
 <div class="reaction_wrapper"> 
   <a href="">
    <img src="img/heart.png">
   </a> 
   <a href=""><img src="img/messagereaction.png"></a> 
   <a href=""><img src="img/message.png"></a>
   <img src="img/save.png" id="changeimg" onclick="changeImage()">  </div>
</div>

Answer 2

The curly bracket on line 7 should be moved to below the else statement. The way it currently is, you're closing the function, and then have an else clause not tied with an if.

Also, setting a to element.src will just copy the value of element.src to the variable a, so if you change a at all it won't change element.src at all. You can fix this by saving a as element so that you can modify the properties, since objects (not primitives) are copied by reference and not value.

function changeImage() {
  let a = document.getElementById("changeimg");
 
  if (a.src === "img/save.png") {
    return a.src "img/saveblack.png"
  } else {
    return a.src = "img/save.png"
  }
}