admin管理员组

文章数量:1200790

Why does this not work?

 <input type="file" id="kmlFiles2" multiple onchange="function(){alert('why does this not work')}()">

chrome gives me an error, Uncaught SyntaxError: Unexpected token (.

Firefox tells me SyntaxError: function statement requires a name.

But this does work?

 <input type="file" id="kmlFiles2" multiple onchange="alert('but this does work')">

/

I am asking because I was was trying to use and MVC framework that injects code into the onchange event.

Why does this not work?

 <input type="file" id="kmlFiles2" multiple onchange="function(){alert('why does this not work')}()">

chrome gives me an error, Uncaught SyntaxError: Unexpected token (.

Firefox tells me SyntaxError: function statement requires a name.

But this does work?

 <input type="file" id="kmlFiles2" multiple onchange="alert('but this does work')">

http://jsfiddle.net/ewzyV/

I am asking because I was was trying to use and MVC framework that injects code into the onchange event.

  • javascript
  • html
  • model-view-controller
  • input
Share Improve this question asked Jun 5, 2014 at 20:38 doodersondooderson 5651 gold badge9 silver badges19 bronze badges 3
  • 1 jsfiddle.net/ewzyV/1 – adeneo Commented Jun 5, 2014 at 20:41
  • ^ if you use a function that executes, for instance an IIFE it should work – adeneo Commented Jun 5, 2014 at 20:41
  • ^ but then, what would be the point ? – adeneo Commented Jun 5, 2014 at 20:42
Add a comment  | 

5 Answers 5

Reset to default 20 
onchange="(function(){alert('this should work')})()"

Its not a good practice to create inline functions.

I would suggest something like 

<html>
 <script>
   function myFunction(){
     alert('hey it works');
   }
 </script>
 <body>
 <input type ='file' id='kmlFiles2' onchange="myFunction();" />
 </body>
 </html>

you can also consider writing

function init(){
   document.getElementById('kmlFiles2').onclick=function(){alert('this also works');};
}
window.onload=init;

you can't call the anonymous function from html element so you can achieve this by event handling like:

<input type="file" id="kmlFiles2" multiple>
 <script>
    document.getElementById("kmlFiles2").addEventListener("change", function(){
        alert('This is working')
    })
 </script>

If you want to use code inside on***="" tag

<input type="text" onchange="{ 
     console.log('anything');
}"

You can just use {} brackets it be like a export default but you still can use this and events

With your code segment:

    onchange="function(){alert('why does this not work')}()"

there is a basic problem. I would expect from https://www.w3schools.com/jsref/event_onchange.asp that the format for JavaScript is (instead):

    object.onchange = function(){myScript};

With the onchange event, the "object." is implicit already, so the expected correct form to use would be:

    onchange= "function(){alert("Why does this not work?"); return;}"

The absence of the return; statement rarely gives problems but - even so - I include it to make the function complete.

I am starting with this reference:
https://www.w3schools.com/js/js_function_definition.asp

After a function expression has been stored in a variable, the variable can be used as a function:
Example:
var x = function (a,b) {return a * b}; var z = x(4, 3);

I found that the following code is working:

    onchange="{alert('Hello 10'); alert('Hello 20'); return; }"

It seems that function() is implicit also. I tested it and the alert posted two times. I started out with just the single alert. Since it works for me, you might want to give this as a hint how it "should" work hopefully for you too.

After testing awhile with the inline functions, they seemed too unstable in order to get something consistently working. So I ended up with the code below that works solidly for me, simply defining a function to do what needs to be done:

<td><strong>Number of Posts For the Carousel to Show:</strong></td>
<td style="text-align: center; vertical-align: middle; padding: 10px;" colspan="2">
<input id="<?php echo esc_attr( $this->get_field_id( 'ceupoststoshow' ) ); ?>" style="vertical-align: middle; horizontal-align: middle;" max="20" min="1" step="1" type="range" value="<?php echo esc_attr( $titleooi ); ?>" onchange="updatetwopoststoshowtext(this.value, this.id, 'ceupoststoshow' , 'titleooi','ceupoststoshowtext')" >
<script type="text/javascript">
function updatetwopoststoshowtext(thistextvalue, thisfieldid, thisoldfromid, thisnewtoidone, thisnewtoidtwo) {
updatepoststoshowtext(thistextvalue, thisfieldid, thisoldfromid , thisnewtoidone);
updatepoststoshowtext(thistextvalue, thisfieldid, thisoldfromid , thisnewtoidtwo);
}
</script>

</td>
<td>
<input style="width: 90%;" type="text" id="<?php echo esc_attr( $this->get_field_id( 'ceupoststoshowtext' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'ceupoststoshowtext') ); ?>" type="text" value="<?php echo esc_attr( $titleooi ); ?>" onchange="updatepoststoshowtext(this.value, this.id, 'ceupoststoshowtext' , 'titleooi')" >
 
<script type="text/javascript">
function updatepoststoshowtext(thistextvalue, thisfieldid, thisoldfromid, thisnewtoid) {
var strthistextvalue= String(thistextvalue); var strthisfieldid = String(thisfieldid); 
var strthisoldfromid=String(thisoldfromid); var strthisnewtoid = String(thisnewtoid);
alert ("UPST hello there! strthistextvalue = " + strthistextvalue + " strthisfieldid = " + strthisfieldid + " strthisoldfromid = " + strthisoldfromid + " strthisnewtoid = " + strthisnewtoid );

var subfieldidlength = strthisfieldid.length - strthisoldfromid.length;
var substrfieldid = strthisfieldid.substring (0, subfieldidlength);
alert ("UPST hello there two! subfieldidlength = " + subfieldidlength + " substrfieldid = " + substrfieldid);

var newstrfieldid = substrfieldid + strthisnewtoid;
alert ("UPST hello there three one! newstrfieldid = " + newstrfieldid);
var newElementId = document.getElementById(newstrfieldid);  
alert ("UPST hello there three two! newElementId.value = " + newElementId.value);
(document.getElementById(newstrfieldid)).value = strthistextvalue;
alert ("UPST hello there three! (document.getElementById(newstrfieldid)).value = " + strthistextvalue);
  
alert ("document.getElementById (newstrfieldid = " +  newstrfieldid + " ) . value = thistextvalue = " + thistextvalue);
return;
}
</script>

本文标签： javascripthtml input onchange doesn39t accept anonymous functionStack Overflow

版权声明：本文标题：javascript - html input onchange doesn&#39;t accept anonymous function - Stack Overflow 内容由网友自发贡献，该文观点仅代表作者本人， 转载请联系作者并注明出处：http://www.betaflare.com/web/1738552462a2097637.html， 本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容，一经查实，本站将立刻删除。