post submit I want to javascript/client side read user input
var h = document.getElementById("myTEXTbox").value;
but the textbox only exists depending earlier user choices. is the an if object exists in javascript?
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Can you rephrase your question? What are you trying to do?Vivin Paliath– Vivin Paliath2014-04-01 16:22:15 +00:00Commented Apr 1, 2014 at 16:22
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3 Answers
check the return of getEelementById, if an element doesnt exist it will return null, and since it is a falsey value you can use it in a if statement.
var element = document.getElementById("myTEXTbox");
var h = element ? element.value : "";
So if element is not null, h will be set to element.value otherwise it will be set to an empty string
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If the object exists then it is an object, if not, it will return undefined!
So you can test it like this:
var element = document.getElementById("myTEXTbox"),
h = (element)? element.value : '';
Basically, you are using this logic: If the element does exist "(element)" or alternatively (el!=undefined) then read the value, if not set the value of 'h' to '' (empty). This could be null or another value.
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Try this:
var element = document.getElementById("myTEXTbox"),
h = element ? element.value : null;
