How can i convert this statement to Jquery Completely

     if(document.getElementById('txt1') != null){
    $("#txt1").val(document.getElementById('txt1').value.toUpperCase());        
}

How can i convert this statement to Jquery开发者_如何学C Completely

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You can use a function with .val() like this:

$("#txt1").val(function(i, val) { return val.toUpperCase(); });

...and it it doesn't find an id="txt1" element it just won't run on any, that's the way jQuery chains work, so your if() check is taken care of as well.

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or like this

var $txt = $("#txt");
if($txt.length){
  $txt.val($txt.val().toUpperCase());
}