Question

I’m new to Javascript and don’t understand the following behaviors.

1. When the textarea is empty, the “process” code doesn’t recognize it as null, and doesn’t prompt for text.

2. When there is text in the textarea, the “process” code does not display the text in the alert. It seems this may be a scope problem I think all my variables are global.

HTML code:

<input type="button" name="btnProcessTA" onclick="myTextArea('process')" value="Process Text Area" />
<input type="button" name="btnClearTA"   onclick="myTextArea('clear')" value="Clear Text Area" />

<form id="formExample" action="" method="get">   
    <label for="textAreaField">A text area field</label>
    <textarea name="textAreaField" id="textAreaField" rows="4" cols="50"></textarea>
</form>

Javascript code:

<script type="text/javascript">
function myTextArea(op)
{
 oTextArea = document.getElementById("textAreaField"); 
 textAreaValue = oTextArea.value;           
 alert(op + "\n" + oTextArea + "\n" + textAreaValue);

 switch (op){
    case "clear":
    oTextArea.value = "";
    alert("Clearing");
    break;

    case "process":
    if (textAreaValue = "")
        alert("Would you please enter some text?"); 
    else
        alert("You entered:\n\n" + textAreaValue);
    break;

    default : alert("unknown op code");
    }
 }
</script>

Answer 1

Change

if (textAreaValue = "")

to

if (textAreaValue === "") // or ==

You are performing assignment instead of doing a comparison.