add text in textarea javascript code example

Example 1: javascript textarea.append

var $log = $('#myTextArea');

function log(text) {
    $log.append(text);
}

// Call log() in your button click event or whichever function 
// you want to use to print to the text area:

//...
log("Hello world!");
//...

Example 2: javascript add text to textarea overwrite

var $log = $('#myTextArea');

function log(text) { //Remember to clear your text variable each iteration
    $log.empty();
    $log.append(text);
}

// Whichever function during which you want to print to the text area:
//...
log("Hello world!");
//...