Remove text from payload

Third party integrations Node-RED
1

My payload is :

msg.payload : string[14]
"amp:volume=38$"

I want to only send 38 in my sensor in home assistant .
what can I do ?
Thx

2

In a Change node, use
Set: msg payload (or whatever you wish) to
to the value J: Expression

and enter the following JSONata expression

$match(payload, /\d+/ )[0].match~>$number()

That performs a regex match for a group of one or more digits [0-9], returns an array of the matches (there should only be one), picks the first match string, and turns it into a number (if you want just the “38” as a string, drop the ~>$number() part).

Should work for you as long as your embedded number is an integer.

[
    {
        "id": "2c0d97e5832a9126",
        "type": "change",
        "z": "e6f8ea0317d4f26a",
        "name": "",
        "rules": [
            {
                "t": "set",
                "p": "payload",
                "pt": "msg",
                "to": "$match(payload, /\\d+/ )[0].match~>$number()",
                "tot": "jsonata"
            }
        ],
        "action": "",
        "property": "",
        "from": "",
        "to": "",
        "reg": false,
        "x": 500,
        "y": 2820,
        "wires": [
            [
                "9aad677dd5839800"
            ]
        ]
    }
]