Reading a JSP variable from JavaScript

Question

How can I read access a JSP variable from JavaScript

User · Answer

The cleanest way  as far as I know    add your JSP variable to an HTML element s data-  attribute then read this value via Javascript when required   My opinion regarding the current solutions on this SO page  reading  directly  JSP values using java scriplet inside actual javascript code is probably the most disgusting thing you could do  Makes me wanna puke  haha  Seriously  try to not do it   The HTML part without JSP    lt body data-customvalueone  1st Interpreted Jsp Value  data-customvaluetwo  another Interpreted Jsp Value  gt      Here is your regular page main content  lt  body gt    The HTML part when using JSP    lt body data-customvalueone    beanName attrName   data-customvaluetwo    beanName scndAttrName   gt      Here is your regular page main content  lt  body gt    The javascript part  using jQuery for simplicity     lt script type  text JavaScript  src    cdnjs cloudflare com ajax libs jquery 2 1 1 jquery js  gt  lt  script gt   lt script type  text javascript  gt      jQuery function            var valuePassedFromJSP      body   attr  data-customvalueone            var anotherValuePassedFromJSP      body   attr  data-customvaluetwo             alert valuePassedFromJSP     and     anotherValuePassedFromJSP     are the values passed from your JSP page         lt  script gt    And here is the jsFiddle to see this in action http   jsfiddle net 6wEYw 2   Resources    HTML 5 data-  attribute  https   developer mozilla org en-US docs Web Guide HTML Using data attributes Include javascript into html file Include JavaScript file in HTML won  39 t work as  lt script        gt  CSS selectors  also usable when selecting via jQuery  https   developer mozilla org en-US docs Web Guide CSS Getting started Selectors Get an HTML element attribute via jQuery http   api jquery com attr

User · Answer

Assuming you are talking about JavaScript in an HTML document   You can t do this directly since  as far as the JSP is concerned  it is outputting text  and as far as the page is concerned  it is just getting an HTML document   You have to generate JavaScript code to instantiate the variable  taking care to escape any characters with special meaning in JS  If you just dump the data  as proposed by some other answers  you will find it falling over when the data contains new lines  quote characters and so on   The simplest way to do this is to use a JSON library  there are a bunch listed at the bottom of http   json org    and then have the JSP output    lt script type  text javascript  gt      var myObject    lt    the string output by the JSON library   gt    lt  script gt    This will give you an object that you can access like   myObject someProperty   in the JS

User · Answer

lt   page contentType  text html  pageEncoding  UTF-8   gt   lt  DOCTYPE html gt   lt html gt   lt head gt       lt meta http-equiv  Content-Type  content  text html  charset UTF-8  gt       lt script  src  https   ajax googleapis com ajax libs jquery 3 4 1 jquery min js  gt            lt title gt JSP Page lt  title gt       lt script gt           document  ready function               lt   String name    phuongmychi github io     gt     jsp vari          var name     lt   name   gt      call var to js              id   html name     output to html                  lt  script gt   lt  head gt   lt body gt       lt h1 id  id  gt   lt  h1 gt   lt  body gt

User · Answer

alert    variable       or  alert   lt   var  gt       or full example   lt html gt    lt head gt   lt script language  javascript  gt    function access        lt   String str  Hello World     gt     var s   lt   str  gt        alert s         lt  script gt    lt  head gt     lt body onload  access    gt    lt  body gt     lt  html gt    Note  sanitize the input before rendering it  it may open whole lot of XSS possibilities

User · Answer

lt   String s  Hi     gt     var v    lt   s  gt

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