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Accessing Java Variables in JavaScript for Web Development
Populating forms dynamically is a common requirement in web development. While Java/JSP/JSTL/EL are powerful tools, accessing their variables in JavaScript can seem challenging. Here's a thorough guide to help you overcome this hurdle:
Understanding the Interplay
Recognize that Java and JSP ultimately generate HTML/CSS/JS code. Your aim is to print Java variables as if they were JavaScript variables, ensuring syntactic validity.
Print Java Variables as JavaScript Variables
To print a Java variable with EL scope (${foo}), utilize the following syntax:
<script>var foo = '${foo}';</script>
This will print:
<script>var foo = 'bar';</script>
Additional Examples
<script>someFunction('${foo}');</script>
<div onclick="someFunction('${foo}')">...</div>
Handle Escaping and Special Cases
Note that single quotes are mandatory for string variables in JavaScript. For user-controlled input, consider XSS attack prevention and JS escaping techniques.
Complex Java Objects
If your variable is a complex Java object (e.g., bean, list, map), use JSON libraries (e.g., Gson) to convert the object to a JSON string. This eliminates the need for quotes:
<script>var foo = ${someObjectAsJson};</script>
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