# Random number from 0 to max of array number

**URL:** <https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560>\
**Category:** General\
**Created:** [7 February 2021 15:30 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560 "2021-02-07T15:30:03Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![vikozo](https://avatars.discourse-cdn.com/v4/letter/v/858c86/32.png) [@vikozo](https://discourse.nodered.org/u/vikozo)\
**Post date:** [7 February 2021 15:30 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/1 "2021-02-07T15:30:03Z")

</div>

Hello  
i found this node geting some quotes and then send it as Telegram  
i have done something similar. but need help for the Random function!

it is "hardcoded" like this  
msg.payload = msg.payload[getRndInteger(0,1642)];

but if i do the http request i would get a array[1643] information  
how to i have to change the function-node to get a random number between 0 and the max array?

```auto
[{"id":"f04fd779.cea4c8","type":"inject","z":"ac8d9bb9.eb8a58","name":"At 11:00am","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"00 11 * * *","once":false,"onceDelay":"","topic":"","payload":"","payloadType":"date","x":170,"y":1380,"wires":[["b031a18e.59b03"]]},{"id":"b031a18e.59b03","type":"http request","z":"ac8d9bb9.eb8a58","name":"","method":"GET","ret":"obj","paytoqs":"ignore","url":"https://type.fit/api/quotes","tls":"","persist":false,"proxy":"","authType":"","x":370,"y":1380,"wires":[["e6a4d14d.ce6a8","348b01d6.0271de"]]},{"id":"e6a4d14d.ce6a8","type":"function","z":"ac8d9bb9.eb8a58","name":"","func":"msg.payload = msg.payload[getRndInteger(0,1642)];\nreturn msg;\n\n// this code gets a random interger\nfunction getRndInteger(min, max) {\n return Math.floor(Math.random() * (max - min + 1) ) + min;\n}","outputs":1,"noerr":0,"initialize":"","finalize":"","x":560,"y":1380,"wires":[["94bfd95f.2c89a8","353a40d8.ac2ca"]]},{"id":"348b01d6.0271de","type":"debug","z":"ac8d9bb9.eb8a58","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":620,"y":1240,"wires":[]}]

```

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [7 February 2021 15:44 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/2 "2021-02-07T15:44:21Z")

</div>

Use `array.length-1` instead of the hard coded value.

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<div class="post-metadata">

**Author:** ![vikozo](https://avatars.discourse-cdn.com/v4/letter/v/858c86/32.png) [@vikozo](https://discourse.nodered.org/u/vikozo)\
**Post date:** [7 February 2021 15:54 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/3 "2021-02-07T15:54:06Z")

</div>

like this  
msg.payload = msg.payload[getRndInteger(0,array.length-1)];

seems to be wrong, i mean i don't get any message anymore

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [7 February 2021 15:55 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/4 "2021-02-07T15:55:51Z")

</div>

Do you have an array variable named `array`?

When I said Use `array.length-1` you are supposed to use your array variable eg myArray.length.

(I'm on my phone so can't load your flow)

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<div class="post-metadata">

**Author:** ![vikozo](https://avatars.discourse-cdn.com/v4/letter/v/858c86/32.png) [@vikozo](https://discourse.nodered.org/u/vikozo)\
**Post date:** [7 February 2021 16:12 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/5 "2021-02-07T16:12:20Z")

</div>

it has no name just  
msg.payload : array[1643]  
and below all the information

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [7 February 2021 16:43 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/6 "2021-02-07T16:43:15Z")

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> [@vikozo](#):
>
> it has no name just

Sure it does. All variables have a name.

> [@vikozo](#):
>
> msg.payload : array[1643]

According to that ^ your array is a property member of the `msg` object named `payload`

So msg.payload.length will be what you use.

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<div class="post-metadata">

**Author:** ![vikozo](https://avatars.discourse-cdn.com/v4/letter/v/858c86/32.png) [@vikozo](https://discourse.nodered.org/u/vikozo)\
**Post date:** [7 February 2021 16:49 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/7 "2021-02-07T16:49:01Z")

</div>

add this like that

> msg.payload = msg.payload[getRndInteger(0, **msg.payload.length** )];

and yes it seems to work  
merci  
vinc

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<div class="post-metadata">

**Author:** ![UnborN](https://avatars.discourse-cdn.com/v4/letter/u/4491bb/32.png) [@UnborN](https://discourse.nodered.org/u/UnborN)\
**Post date:** [7 February 2021 17:13 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/8 "2021-02-07T17:13:26Z")

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> [@vikozo](#):
>
> msg.payload = msg.payload[getRndInteger(0, **msg.payload.length** )];

You forgot to add the -1 .. and in some very rare occusion you may get a random number outside the length of the array that starts from 0.

So as Steve suggested  
`msg.payload = msg.payload[getRndInteger(0, msg.payload.length - 1 )];`

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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 17:14 UTC](https://discourse.nodered.org/t/random-number-from-0-to-max-of-array-number/40560/9 "2021-02-21T17:14:26Z")

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