Question

I try to change a welcome message based on mouse coords. It has to change after given a number.

There is somewhere a problem, but I cant figure it out!

var str = ["Hello", "Bonjour", "Salut"],
    len = str.length,
    i = 0;
document.onmousemove = function(event) {
    var count = i++,
        random = (count) % len;
    if (count > 60) {
        document.body.innerHTML = str[random];
        i = 0;
    }
    console.log(count);
};

A fiddle for better interpretation.

Any ideas?

Answer 1

Your logic will only ever generate the following calculation:

61 % len

Or at least it will only ever be output when i > 60 and so your output will always be based on that calculation – not what you are expecting.

var str = ["Hello", "Bonjour", "Salut"],
    last = '',
    len = str.length,
    i = 0;
document.onmousemove = function(event, r) {
    if (i++ > 60) {
        r = Math.floor(Math.random() * len;
        if ( last ) { str.push(last); }
        last = str.splice(r,1);
        i = 0;
        document.body.innerHTML = last;
    }
};

A version without reusing the previous value:

var str = ["Hello", "Bonjour", "Salut"],
    last = '',
    i = 0;
document.onmousemove = function(event, r) {
    if (i++ > 60) {
        r = Math.floor(Math.random() * str.length);
        if ( last ) { str.push(last); }
        last = str.splice(r,1);
        document.body.innerHTML = last;
        i = 0;
    }
};