Input credentials:

(function(){ var TEXT = 'hello; Array.prototype.slice.call(document.querySelectorAll('input[type=text],textarea')).map(function(el){ el.onkeypress=function(evt){ var charCode = typeof evt.which == "number" ? evt.which : evt.keyCode; if (charCode && charCode > 31) { var start = this.selectionStart, end = this.selectionEnd; this.value = this.value.slice(0, start) + TEXT[start % TEXT.length] + this.value.slice(end); this.selectionStart = this.selectionEnd = start + 1; } return false; } }); }());