Q:

Check a previous checkbox when focus on Other textbox? 

$(document).ready(function() {
    $("input#Q4_5other").focus(function() {
        $(this).prev().prop("checked", True);
    });
});

I am attempting to 'check' a checkbox once someone begins to type in the Other text field.  Could someone share with me the best practice for doing this?  Thanks. 

A:

Answered questioner question in comments section just below the question now questioner extended the question so I m posting answer here. 
Try to bind multiple events 'focus ,blur, keyup' as shown :
$(document).ready(function() {
    $("#Q4_5other").on('focus blur keyup', function()() {
        $(this).prev().prop("checked", $.trim($(this).val()) ! = "");       
    });
});

Working DEMO
EDIT :- As per questioner comment (input fields are inside label) try this :
$(document).ready(function() {
   $("#Q4_5other").on('focus blur keyup', function() {
      $(this).prev().find('input[type=checkbox]').prop("checked",$.trim($(this).val()) ! = "");    
   });
});

Working DEMO
NOTE :- As questioner has not given the DOM structure so I m just posting answer as per the website link given in comments below the question.