javascript click event handler fires without clicking

Question

Why does this function get fired without having clicked on the specified button? I had a look at a few similar problems but none deal with this code structure (might be obvi

Answer 1

This code executes your function hideId("main") you should pass just the callback's name:

document.getElementById("main_btn").addEventListener("click", hideId);

function hideId(event) {
    var id = event.target.srcElement.id; // get the id of the clicked element
    document.getElementById(data).style.display = "none";
    console.log("hidden element #"+data);
}

Answer 2

You are directly calling it.

document.getElementById("main_btn").addEventListener("click", hideId("main");

You should do that in a callback.

document.getElementById("main_btn").addEventListener("click", function (){
    hideId("main");
});

Answer 3

document.getElementById("main_btn").addEventListener("click", hideId.bind(null, "main");