CODE EXAMPLE FOR JAVASCRIPT

iframe set value on input outside js

var input = document.getElementById('input-field');

window.addEventListener('message', function(e) {
    // Check the origin, accept messages only if they are from YOUR site!
    if (/^http://www.mysite1.com/.test(e.origin)) {
        input.value = e.data; 
        // This will be 'Something something something'
    }
});