How to pass java string variable to the javascript function by jsp expression tag?

java javascript jsp

16,831

Solution 1

Try using single quote ' when using string in HTML:

onclick= "stringGenerate('<%=str %>')"
                         ^        ^

Full Code:

<input type="button" value="String Generate" onclick= "stringGenerate('<%=str %>')" />

Solution 2

The reason is that when the page is rendered by the browser, it puts the str and num values directly in the code, so it looks like:

<input type="button" value="String Generate" onclick="stringGenerate(abcdefghij)"/>

The browser basically thinks you're trying to reference a Javascript variable called 'abcdefghij'.

You should add the ' chars before and after your string text to let javascript know it should use the value of that text and not search for a variable with that name.

The declaration of str should look like this to make it work:

String str = "\'abcdefghij\'";

Please note, you can't use \" to escape as this would break your code.

16,831

Author by

Aditya

Updated on July 18, 2022

Comments

Aditya almost 2 years

I want to passing a java String variable to the javascript function parameter using jsp expression tag.Below is my jsp page.

First.jsp

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
        <title>Insert title here</title>
        <script>
            function stringGenerate(str){
                var x = document.getElementsByTagName("input");
                x[0].value = str;
            }
            function numberGenerate(num){
                var x = document.getElementsByTagName("input");
                x[1].value = num;
            }
        </script>
    </head>
    <body>
        <%
            String num ="1234567890";
            String str = "abcdefghij";
        %>

        <input type="text" name="string" readonly="readonly"/> &nbsp;&nbsp;
        <input type="text" name="number" readonly="readonly"/><br/><br/>

        <input type="button" value="String Generate" onclick= "stringGenerate(<%=str %>)" /> &nbsp;&nbsp;
        <input type="button" value="Number Generate" onclick= "numberGenerate(<%=num %>)" />
    </body>
</html>

When I click on the button with value "Number Generate",then the num variable value(1234567890) will display on the textbox(name="number") but when I click on the button with value "String Generate",then there is nothing display on the corresponding text box(name="string").Here both num and str are string type varible but why only num variable value is displayed on textbox and why not str variable value is displayed?