# .toISOstring() is not a function

**URL:** <https://discourse.nodered.org/t/toisostring-is-not-a-function/40587>\
**Category:** General\
**Created:** [7 February 2021 23:29 UTC](https://discourse.nodered.org/t/toisostring-is-not-a-function/40587 "2021-02-07T23:29:06Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![jerbzz](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/jerbzz/32/32673_2.png) [@jerbzz](https://discourse.nodered.org/u/jerbzz)\
**Post date:** [7 February 2021 23:29 UTC](https://discourse.nodered.org/t/toisostring-is-not-a-function/40587/1 "2021-02-07T23:29:06Z")

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Hi team,

I'm making a function node:

```auto
var newmsg = { payload: { results: [] } };
var duration = 0;
var numslots = 0;
var newslots = 0;

for (let i = 0; i < msg.payload.results.length; i++ ) {

    duration = Date.parse(msg.payload.results[i].valid_to) - Date.parse(msg.payload.results[i].valid_from);
    newslots = duration / 3600000;
    
        for (let j = 0; j < newslots; j++ ) {
            var data = { };
            
            var valid_from_millis = parseInt(Date.parse(msg.payload.results[i].valid_from), 10) + (j * 1800000);
            var validfrom = new Date(valid_from_millis);
            data.valid_from = validfrom.toISOstring();
            
            data.value_exc_vat = msg.payload.results[i].value_exc_vat;
            data.value_inc_vat = msg.payload.results[i].value_inc_vat;
            
            newmsg.payload.results.push (data);
            numslots++;
        }
}

newmsg.payload.count = numslots;

return newmsg;

```

I keep getting this error: ` TypeError: validfrom.toISOstring is not a function`

I know this happens when you try to call `.toISOstring` on something that isn't a `Date` - but I think I am calling it on a `Date`?

Any advice greatly appreciated.

Thank you

James

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<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [7 February 2021 23:36 UTC](https://discourse.nodered.org/t/toisostring-is-not-a-function/40587/2 "2021-02-07T23:36:19Z")

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`toISOstring` should be `toISOString`

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<div class="post-metadata">

**Author:** ![jerbzz](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/jerbzz/32/32673_2.png) [@jerbzz](https://discourse.nodered.org/u/jerbzz)\
**Post date:** [7 February 2021 23:40 UTC](https://discourse.nodered.org/t/toisostring-is-not-a-function/40587/3 "2021-02-07T23:40:41Z")

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SON OF A.... MONKEY!

Thanks!

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [21 February 2021 23:41 UTC](https://discourse.nodered.org/t/toisostring-is-not-a-function/40587/4 "2021-02-21T23:41:20Z")

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