通过javascript警告文本框

Question

very simple question! i was wondering how to use javascript to alert something in my textbox...not sure what i'm doing now is not working. heres the function

function alertNow(comment){
alert(comment);
}

now here is the textbox

<input type = 'text' name = 'txt_comment'>
<button onClick = alertNow(txt_comment.value) value = "Submit Comment"></button> 

sure this is doable, i did it before but i just forgot some syntax prob. any ideas? thanks!

Answer 1

You are missing quotations. Also use the ID instead of name.

<input type = 'text' name = 'txt_comment' id='txt_comment'>
<button onClick = 'alertNow(txt_comment.value)' value = "Submit Comment"></button> 

Also better to use, document.getElementById like below

 <button onClick = 'alertNow(document.getElementById("txt_comment").value)' value = "Submit Comment"></button> 

Answer 2

<input type="text" id="testTextarea">
<input type="submit" value="Test" onClick="alert(document.getElementById('testTextarea').value);" />

Answer 3

function alertNow() {
 var a = document.getElementById("txt_comment").value;
 alert (a);
}

<input type = 'text' name = 'txt_comment' id="txt_comment">
<button onClick = "alertNow()" value= "Submit Comment"></button>

Answer 4

here is the code to complete your task...

// js code ...

function alertNow(){
   alert(document.getElementById('txt_comment').value);
   return false;
}

// html code ....

<form name="form_1" id="form_1" method="post">
     <input type = 'text' id='txt_comment' name = 'txt_comment'>
     <input type="button" onClick = "return alertNow();" value = "Submit Comment"/> 
</form>  

Answer 5

Use the ID instead of name.

function alertText() { alert(document.getElementById('txt_comment').value); }

<input type = 'text' name = 'txt_comment' id="txt_comment"> 
<button onClick = "alertText()" value= "Submit Comment"></button>