Placeholder.js fast usage.

placeholder.js

window.onload = function() { 
    var form = document.getElementById('form'),
        placeholderTestElm = document.createElement('input'),
        isSupported = !(undefined === placeholderTestElm.placeholder);

    if (!isSupported) { 
        this.initPlaceholder();

        form.onsubmit = function(e) {
            alert('After this point all inputs without values and with placeholder should be clear.');
        }
    } else {
        alert('Sorry but the browser you are currently using have native placeholder support implemented. Try with older one.')
    }
}