window.onload=init;
function init(){
    var x=document.getElementsByTagName('a');
    for(var i in x){
        x[i].onclick=function(){
            return confirm('are you sure?');
        }
    }
}

Can be run successfully

But writing it in the following form cannot run correctly. return false is not captured. When cancel is clicked, the link still jumps. Why is this?

The functions are as follows:

window.onload=init;
function init(){
    var x=document.getElementsByTagName('a');
    for(var i in x){
        x[i].onclick=function(){
        ask();
        }
    }
}
function ask(){
    return confirm('are you sure?');
}

can be run correctly if written in the following form:

window.onload=init;
function init(){
    var x=document.getElementsByTagName('a');
    for(var i in x){
        x[i].onclick=ask;
    }
}
function ask(){
    return confirm('are you sure?');
}

Please tell me the difference between the three writing methods