Call a java script function for all targeted elements

Question

I found a javascript function that I want to apply to all targeted elements, in my case all textarea from page but when I am changing the selector from document.getElementById('text'); into document.querySelectorAll('textarea'); or document.getElementsByTagName('textarea') in order to target all elements is not working and I don't understand why, I have tried to put text variable in a for but still not working, if someone can help me a little bit with this dummy issue :|

Answer 1

You were on the right track with a loop, you just didn't go far enough (see comments):

function init () {
    var list, i, text;

    // Get the list
    list = document.getElementsByTagName('textarea');

    // Loop through it
    for (i = 0; i < list.length; ++i) {
        // Get this entry
        text = list[i];

        // Do things with it
        observe(text, 'change',  resize);
        observe(text, 'cut',     delayedResize);
        observe(text, 'paste',   delayedResize);
        observe(text, 'drop',    delayedResize);
        observe(text, 'keydown', delayedResize);

        // Initial `resize` call -- I'm using `.call` in order to
        // set `this` to the element during the call, like an event
        // does
        resize.call(text);

        // You'll have to choose *one* of them to focus; I chose the first
        if (i == 0) {
            text.focus();
            text.select();
        }
    }
    function resize () {
        // Note that I'm using `this` here, not `text` or `list`
        // `this` will refer to the element the event is occurring on
        this.style.height = 'auto';
        this.style.height = this.scrollHeight+'px';
    }

    // 0-timeout to get the already changed text
    function delayedResize () {
        // Again note the use of `this`, also `.bind`.
        // `Function#bind` creates a function that, when called,
        // calls the original with a specific `this` value
        window.setTimeout(resize.bind(this), 0);
    }
}