AJAX Basics

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AJAX Basics
xhr new XMLHttpRequest() xhr.onreadystatechange
xhrHandler xhr.open("POST",
url) xhr.send(postData) ... function
xhrHandler() if (this.readyState ! 4)
return if (this.status ! 200) //
Handle error ... return ... var
text this.responseText var document
this.responseXML
State 4 means done
Response available as raw text or XML
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JSON Example
name "Alice", gpa 3.5, friends "Bill",
"Carol", "David"
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Higher-Level AJAX Example
lt form.text_field(userName) gt ... ltdiv
id"completionMenu"gt...lt/divgt ... lt
observe_field( form_userName, frequency
gt 0.25, update gt
"completionMenu", url gt action
gt "nameChoices" ) gt class FooController lt
ApplicationController def nameChoices
... end
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Higher-Level AJAX Example
lt form.text_field(userName) gt ... ltdiv
id"completionMenu"gt...lt/divgt ... lt
observe_field( form_userName, frequency
gt 0.25, update gt
"completionMenu", url gt action
gt "nameChoices" ) gt class FooController lt
ApplicationController def nameChoices
... end
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