javascript - Pass text of input to calling function (yes it is possible) -

i know question has been asked -and answered- multiple times. found new solution - not understand it. setup this:

<input id="input1" onchange="gettext()"/> 

all answers found suggest use id value of input.

function gettext(){   alert($("#input1").val()); } 

$(this).val() not work here.

another way use value of #input1 use this.value in calling function:

<input id="input1" onchange="gettext(this.value)" /> 

this passes value parameter function.

however found jquery sample attaches function #input1 , makes $(this).val() work.

$("#input1").change(function(e){ alert($(this).val()) }); 

against answers here @ stackoverflow seeing possible attach function input field , have access value of - ask myself how have write function , not attach jquery. or can attached jquery? why?

here fidle setup play

you either pass reference input object parameter in inline call callback this:

<input id="input2" onchange="gettext(this)" /> 

and in javascript:

function gettext(_this){   alert(_this.value); } 

fiddle here

or can attach function directly input object so

document.getelementbyid('input2').gettext = function() {     alert(this.value); }; 

and in html:

<input id="input2" onchange="this.gettext()" /> 

fiddle here

basically object in javascript bound context, in function has been created. when define function globally, gettext in example, bound global object in scope of function.