Find Max Value In an Array: Best Node-Red Way

[n61ab]

I have an array in flow context and want to find the maximum number value.

I have tried several of the Javascript math functions, with no success.

Is there a contrib node for finding the maximum value in an array?

Else, need help with a function. Here is my failed attempt. It always returns 0.

Alan

[Steve-Mcl]

0 is the max number. Am I missing something?

[n61ab]

Thanks, Steve

dahhhhh. I am so a embarrassed!

By the way, I am having fun building a Signal Strength Dashboard gauge using your SVG node and the "binding" tab, hence the negative numbers. I am climbing the SVG learning curve. I want to add a marker for the maximum value, hence the function to find the "min" value.

Here is a screenshot. I used your "window shade" example to build the gauge graphic and like your example, am moving the black rectangle to expose the gauge level element.

[hotNipi]

SVG is fun for sure, but is it really needed to be that complex.
This kind of stuff is easy enough to achieve with basic HTML elements.

[{"id":"8d516329880a7b2d","type":"random","z":"9141c3fbcc7d9e2b","name":"","low":"-100","high":"0","inte":"true","property":"payload","x":480,"y":520,"wires":[["463566f7274c285b"]]},{"id":"a230737c1703a91e","type":"inject","z":"9141c3fbcc7d9e2b","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"3","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":310,"y":520,"wires":[["8d516329880a7b2d"]]},{"id":"d02a005c014fb48b","type":"ui_template","z":"9141c3fbcc7d9e2b","group":"f6124e036e2d2ffb","name":"DIY level","order":0,"width":0,"height":0,"format":"<style>\n.level{\n  position:absolute;\n  inset:0;\n  top:50%;\n  bottom:15%;\n  background:repeating-linear-gradient( 90deg, green, green 5px, transparent 5px, transparent 8px);\n  width:calc(1% * var(--size));\n}\n.value{\n  position:absolute;\n  text-align:center;\n  inset:0;\n}\n.limits{\n  font-size:10px;\n}\n.min{\n  position:absolute;\n}\n.max{\n  position:absolute;\n  right:0;\n  margin-right:4px;\n}\n.top{\n  background:red;\n  position:absolute;\n  inset:0;\n  top:95%;\n  width:calc(1% * var(--top));\n  \n}\n</style>\n\n<div id=\"{{'level_min_'+$id}}\" class=\"limits min\">-100</div>\n<div id=\"{{'level_max_'+$id}}\" class=\"limits max\">0</div>\n<div id=\"{{'level_val_'+$id}}\" class=\"value\"></div>\n<div id=\"{{'level_'+$id}}\" class=\"level\"></div>\n<div id=\"{{'level_top'+$id}}\" class=\"top\"></div>\n\n<script>\n    (function(scope) {\n      const min = -100\n      const max = 0\n      const label = \"DIY Level \"\n      const unit = \" dBm\"\n  scope.$watch('msg', function(msg) {\n    if (msg) {\n      // Do something when msg arrives\n      const v = Math.floor(((msg.payload - min) / (max - min)) * 100);\n      const t = Math.floor(((msg.top - min) / (max - min)) * 100);\n      document.getElementById('level_'+scope.$id).style.setProperty('--size', v);\n      document.getElementById('level_top'+scope.$id).style.setProperty('--top', t);\n      document.getElementById('level_val_'+scope.$id).textContent = label + msg.payload + unit;\n    }\n  });\n})(scope);\n</script>","storeOutMessages":true,"fwdInMessages":true,"resendOnRefresh":true,"templateScope":"local","className":"","x":780,"y":520,"wires":[[]]},{"id":"463566f7274c285b","type":"function","z":"9141c3fbcc7d9e2b","name":"","func":"let last = context.get('last') || Number.MIN_SAFE_INTEGER\nif(msg.payload > last){\n    last = msg.payload;\n    context.set('last',last)\n}\nmsg.top = last\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":620,"y":520,"wires":[["d02a005c014fb48b"]]},{"id":"f6124e036e2d2ffb","type":"ui_group","name":"Default","tab":"34ab7d39f3e308fc","order":1,"disp":true,"width":"6","collapse":false,"className":""},{"id":"34ab7d39f3e308fc","type":"ui_tab","name":"Home","icon":"dashboard","disabled":false,"hidden":false}]

[n61ab]

Thanks, hotNipi

I am very low on the learning curve and found the SVG node a "low code" way to build my meter.

I want to learn HTML. Could you point me to some references (starting points) to learn how you built the DYI meter?

Alan

[hotNipi]

To get started, it takes to get started.
All about the HTML
All about the CSS
Stripes with CSS
And everything else is mostly written into ui_template node's help page

Of course it takes some time to get it going cos you kind of need to learn 3 languages at same time. But they are tightly connected so it seems like one.

And the web is full of examples and explanations - key is to learn how to search and how to use tips and tricks to achieve what ever you are targeting.

[n61ab]

Thanks. Lot of learning.

Alan