{"id":5183,"date":"2022-08-27T02:48:15","date_gmt":"2022-08-26T21:18:15","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-return-javascript-function-in-jsp-form-closed\/"},"modified":"2022-08-27T02:48:15","modified_gmt":"2022-08-26T21:18:15","slug":"solved-return-javascript-function-in-jsp-form-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-return-javascript-function-in-jsp-form-closed\/","title":{"rendered":"[Solved] return javascript function in JSP form [closed]"},"content":{"rendered":"

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It seems like you’re confused about a basic part of html, and programming languages in general: Contexts. html is constructed out of tags. A tag may contain attributes, which may have a value.<\/p>\n

In a tree-like form:<\/p>\n

tag\n | attribute = value\n | attribute\ntag\n | attribute = value\ntag\ntag\n | attribute\n...\n<\/code><\/pre>\n
Or more concretely:<\/p>\n
<input type=\"password\" hidden \/>\n<img src=\"https:\/\/stackoverflow.com\/questions\/23348596\/goat.png\" \/>\n<div>Blah<\/div>\n<\/code><\/pre>\n
When the browser (and you) go over a tag and try to understand it, it expects certain characters. it knows that <<\/code> starts a tag, that ><\/code> ends it, that after the <<\/code> comes the tag name, and so forth. Going over some text and extracting meaning is called “parsing”, and the rules you follow are called “grammar”.<\/p>\n
In our example above, the browser sees <input type=\"password\" hidden \/><\/code>, and can break it down into the following:<\/p>\n
<input type=\"password\" hidden \/>\n       ^-------------^ ^----^\n          attr=value    attr\n^------------------------------^\n              tag\n<\/code><\/pre>\n
The html grammar does not allow you to specify a tag within an attribute’s value. It just treats it like a regular value.<\/p>\n
<input type=\"password\" value=\"<div>blah<\/div>\" \/>\n       ^-------------^ ^---------------------^\n          attr=value          attr=value\n^-----------------------------------------------^\n                       tag\n<\/code><\/pre>\n
When you think about it, it makes much more sense: What does it mean for a value to be a tag? What does value=\"<div>blah<\/div>\"<\/code> do<\/em>? How do you make sense of it?<\/p>\n
So we reach our problem: html is static, but you want to change it dynamically. Enter javascript and the DOM (Document Object Model):<\/p>\n
var input = magically_get_the_input_element();\ninput.value = get_deviceprint();\n<\/code><\/pre>\n
The DOM is the result of parsing the html into objects you can interact with using javascript. That means that you can manipulate a page, which is exactly what you want. It’s a big topic, and I won’t endeavour to cover it in here, but here are some pointers to where you can learn about javascript and the DOM:<\/p>\n