Working in Node-Red. I can use regular global variables across nodes and flows no problem. However, would like to use a global array variable.
Method A - desired functionality I read in 16 data points at a time (type = double) and want to have them be index 0-15, then the following node would update indexes 16-31; then 32-45 and 46-64 in the last two nodes.
Node Red however, won't let update the array from the second node starting from index #16. I get "TypeError: Cannot read property 'indexOf' of undefined" error.
In lieu of Method A, I could have four different 16-index global arrays. However, accessing them gives erratic results. Trying to access index[n] returns the value from some other index - i.e. global.get("variable"[0]) returns variable[10] and global.get("variable"[1]) returns the value from variable[27].
This describes the problem - https://www.youtube.com/watch?v=cF1bz8bEozI
Here is my sample flow:
[{"id":"ee1694d.7df4768","type":"i2c in","z":"d556390c.391838","name":"Read Camera","address":"105","command":"128","count":"32","x":240,"y":1480,"wires":[["9e27949c.512c28"]]},{"id":"d9eaa7a4.7f0ed8","type":"inject","z":"d556390c.391838","name":"ON","topic":"1","payload":"1","payloadType":"str","repeat":"","crontab":"","once":false,"x":70,"y":1480,"wires":[["ee1694d.7df4768"]]},{"id":"6dc0727a.4cf53c","type":"i2c in","z":"d556390c.391838","name":"Read Camera","address":"105","command":"160","count":"32","x":240,"y":1520,"wires":[["a7ac4b94.44ce58"]]},{"id":"d6d80973.784148","type":"i2c in","z":"d556390c.391838","name":"Read Camera","address":"105","command":"192","count":"32","x":240,"y":1560,"wires":[["b90d910d.8e743","ebeeb439.54cf18"]]},{"id":"b90d910d.8e743","type":"i2c in","z":"d556390c.391838","name":"Read Camera","address":"105","command":"224","count":"32","x":240,"y":1600,"wires":[["2f7b8dde.7a9902"]]},{"id":"6b1509e2.8bd4d8","type":"debug","z":"d556390c.391838","name":"Row 3,4","active":true,"console":"false","complete":"payload","x":1020,"y":1520,"wires":[]},{"id":"a828b6d2.40da08","type":"delay","z":"d556390c.391838","name":"","pauseType":"delay","timeout":"50","timeoutUnits":"milliseconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"x":98,"y":1656,"wires":[["d6d80973.784148"]]},{"id":"ad0a1424.eaae08","type":"function","z":"d556390c.391838","name":"Save Global variables for Temperature","func":"global.set(\"RangeTemperaturesA\", 0);\n\nfor(i=0; i<16; i++){\n global.set(\"RangeTemperaturesA\"[i], msg.payload[i]); \n}\n\nreturn msg;","outputs":1,"noerr":0,"x":750,"y":1480,"wires":[["6b810d97.0beee4","6dc0727a.4cf53c"]]},{"id":"d386a34f.525d2","type":"function","z":"d556390c.391838","name":"Save Global variables for Temperature","func":"for(i=0; i<16; i++){\n global.set(\"RangeTemperatureB\"[i], msg.payload[i]); \n}\n\nreturn msg;","outputs":1,"noerr":0,"x":750,"y":1520,"wires":[["6b1509e2.8bd4d8"]]},{"id":"11c935c.be330ca","type":"function","z":"d556390c.391838","name":"Save Global variables for Temperature","func":"for(i=0; i<16; i++){\n global.set(\"RangeTemperatureC\"[i], msg.payload[i]); \n}\n\nreturn msg;","outputs":1,"noerr":0,"x":750,"y":1560,"wires":[[]]},{"id":"294185a.d5fe67a","type":"function","z":"d556390c.391838","name":"Save Global variables for Temperature","func":"for(i=0; i<16; i++){\n global.set(\"RangeTemperatureD\"[i], msg.payload[i]); \n}\n\nreturn msg;","outputs":1,"noerr":0,"x":750,"y":1600,"wires":[[]]},{"id":"3ffa9e84.cba002","type":"function","z":"d556390c.391838","name":"Find Max Temperature","func":"//n = Math.max(... global.get(\"RangeTemperature\"));\n\nreturn {payload: global.get(\"RangeTemperature\")};","outputs":1,"noerr":0,"x":900,"y":1660,"wires":[[]]},{"id":"9e27949c.512c28","type":"function","z":"d556390c.391838","name":"Get Temps full row","func":"var gridEye = [];\nvar loop=0;\n\nfor(n=0; n<32; n+=2){\n gridEye[loop] = ((msg.payload[n+1]<<8) | msg.payload[n]) * 0.25;\n //convert to F\n gridEye[loop] = ((5.0/3.0) * gridEye[loop] + 32.0).toFixed(2);\n //add right bitshit to reduce noise\n loop++;\n}\nmsg.payload=gridEye;\n\nreturn msg;","outputs":1,"noerr":0,"x":490,"y":1480,"wires":[["ad0a1424.eaae08"]]},{"id":"a7ac4b94.44ce58","type":"function","z":"d556390c.391838","name":"Get Temps full row","func":"var gridEye = []; //16-byte array with temperature readings\nvar loop=0;\n\nfor(n=0; n<32; n+=2){\n // Get raw values - bitshift left 8 bits then bitwise OR.\n // then take new value and multiply by 0.25 since it reads in 1/4 degree C\n gridEye[loop] = ((msg.payload[n+1]<<8) | msg.payload[n]) * 0.25;\n //convert to F\n gridEye[loop] = ((5.0/3.0) * gridEye[loop] + 32.0).toFixed(2);\n loop++;\n}\n\nmsg.payload=gridEye;\n\nreturn msg;","outputs":1,"noerr":0,"x":490,"y":1520,"wires":[["d386a34f.525d2"]]},{"id":"ebeeb439.54cf18","type":"function","z":"d556390c.391838","name":"Get Temps full row","func":"var gridEye = [];\nvar loop=0;\n/*\nvar pixel = 4;\nvar tmp = ((msg.payload[pixel*2 + 1]<<8) | msg.payload[pixel*2])*0.25; \n//gridEye reads in .25 degree C\ntmp = ((5/3 * tmp) + 32.0); //convert to F\n*/\n\nfor(n=0; n<32; n+=2){\n gridEye[loop] = ((msg.payload[n+1]<<8) | msg.payload[n]) * 0.25;\n //convert to F\n gridEye[loop] = ((5.0/3.0) * gridEye[loop] + 32.0).toFixed(2);\n //add right bitshit to reduce noise\n loop++;\n}\n/*\nfor(n=0; n<8; n++){\n gridEye[n]= ((n/35536 * 60 ) + 20);\n //convert to F\n //gridEye[n] = (((5.0/3.0) * gridEye[n]) + 32).toFixed(2);\n}\n*/\nmsg.payload=gridEye;\n\nreturn msg;","outputs":1,"noerr":0,"x":490,"y":1560,"wires":[["11c935c.be330ca"]]},{"id":"2f7b8dde.7a9902","type":"function","z":"d556390c.391838","name":"Get Temps full row","func":"var gridEye = [];\nvar loop=0;\n/*\nvar pixel = 4;\nvar tmp = ((msg.payload[pixel*2 + 1]<<8) | msg.payload[pixel*2])*0.25; \n//gridEye reads in .25 degree C\ntmp = ((5/3 * tmp) + 32.0); //convert to F\n*/\n\nfor(n=0; n<32; n+=2){\n gridEye[loop] = ((msg.payload[n+1]<<8) | msg.payload[n]) * 0.25;\n //convert to F\n gridEye[loop] = ((5.0/3.0) * gridEye[loop] + 32.0).toFixed(2);\n //add right bitshit to reduce noise\n loop++;\n}\n/*\nfor(n=0; n<8; n++){\n gridEye[n]= ((n/35536 * 60 ) + 20);\n //convert to F\n //gridEye[n] = (((5.0/3.0) * gridEye[n]) + 32).toFixed(2);\n}\n*/\nmsg.payload=gridEye;\n\nreturn msg;","outputs":1,"noerr":0,"x":490,"y":1600,"wires":[["294185a.d5fe67a"]]},{"id":"a0de3101.0c307","type":"function","z":"d556390c.391838","name":"Read from A","func":"var p = global.get(\"RangeTemperaturesA\"[1]);\nmsg.payload = p;\nreturn msg;","outputs":1,"noerr":0,"x":510,"y":1780,"wires":[["dbb0935d.742f7"]]},{"id":"dbb0935d.742f7","type":"debug","z":"d556390c.391838","name":"test A","active":true,"console":"false","complete":"payload","x":670,"y":1860,"wires":[]},{"id":"f6c50374.59f","type":"function","z":"d556390c.391838","name":"Read from B","func":"var n = global.get(\"RangeTemperatureB\"[0]);\nreturn {payload: n};","outputs":1,"noerr":0,"x":770,"y":1780,"wires":[["3e8947bc.be49b8"]]},{"id":"6b810d97.0beee4","type":"debug","z":"d556390c.391838","name":"Row 1,2","active":true,"console":"false","complete":"payload","x":1020,"y":1480,"wires":[]},{"id":"3e8947bc.be49b8","type":"debug","z":"d556390c.391838","name":"test b","active":true,"console":"false","complete":"payload","x":910,"y":1860,"wires":[]},{"id":"23da3f7f.1c4f8","type":"inject","z":"d556390c.391838","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":340,"y":1780,"wires":[["a0de3101.0c307"]]},{"id":"2a146fa7.577fc","type":"inject","z":"d556390c.391838","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":580,"y":1720,"wires":[["f6c50374.59f"]]}]
Edit - I did a quick test - For global.set -
global.set("RangeTemperaturesA", i)[i]; gives "TypeError: Cannot read property '0' of undefined"
global.set("RangeTemperaturesA[i]", i); gives "Error: Invalid property expression: unexpected i at position 19"
global.set("RangeTemperaturesA"[i], i); appears to probably work.
Sample code:
for(i=0; i<16; i++){
global.set("RangeTemperaturesA"[i], i);
node.warn("Value: " + i);
}
return msg;
Global.get -
global.get("RangeTemperaturesA"[n]) gives erratic results.
global.get("RangeTemperaturesA[n]") gives "Error: Invalid property expression: unexpected n at position 19"
global.get("RangeTemperaturesA")[n] gives "Value: undefined; Count: 0" gives "Value: undefined; Count: 0" which is perhaps the most promising if the array was never populated correctly.
Sample code:
for(n=0; n<16; n++){
node.warn("Value: " + global.get("RangeTemperaturesA")[n] + "; Count: " + n);
}
return msg;
The problem is due to the way you're trying to address the individual array entries.
With the code: global.get("variable"[0]), you are asking it to use the 0th element of the string "variable" as the argument passed to the get function. In otherwords, it is equivalent to: global.get("v")
Similarly, global.get("variable"[2]) will be equivalent to global.get("r").
You should either move array index inside the quotes:
global.get("variable[0]");
or access the 0th element of the result of the get function:
global.get("variable")[0];
The same holds true for how you are trying to use the set function.
Updates to reflect edits to the quesiton
None of your attempts to use global.set() are correct:
global.set("RangeTemperaturesA", i)[i] - here you are setting the global property RangeTemperaturesA to the value of i. The function set doesn't return anything, so attempting to treat it as an array is just wrong.
global.set("RangeTemperaturesA[i]", i); - this is the closest of the three, however, you are setting the string literal RangeTemperaturesA[i] - JavaScript doesn't know you want the i in the middle of that string to be the value of your local variable i.
global.set("RangeTemperaturesA"[i], i); - no. This is the same error as you had in the original question. "RangeTemperaturesA"[i] will evalute to the ith character of the string RangeTemperaturesA.
To do it properly, you want to use "RangeTemperaturesA["+i+"]" as the key:
global.set("RangeTemperaturesA["+i+"]", i);
When i is 0, that will generate the key RangeTemperaturesA[0].
The same applies for global.get:
var myValue = global.get("RangeTemperaturesA["+i+"]");
All of these examples assume you have already set RangeTemperaturesA to be an array:
global.set("RangeTemperaturesA",[]);