CSV node crashes with TypeError: Cannot read properties of undefined (reading 'includes') when CSV starts with delimiter

Author: codeCraft-RitikCreated Sep 8, 2026Updated Sep 8, 2026

Labelsneeds-triage

Current Behavior

When using the csv node in Legacy mode to parse a CSV string where the first column is empty (i.e. the line begins with a separator delimiter such as ,1,2,3\n or \tval1\tval2\n), the parser crashes with:

TypeError: Cannot read properties of undefined (reading 'includes')
    at @node-red/nodes/core/parsers/70-CSV.js:233:85
    at Node.emit (node:events)

In packages/node_modules/@node-red/nodes/core/parsers/70-CSV.js at line 233, the code checks:

javascript

if (line[i-1] === node.sep || line[i-1].includes('\n','\r')) k[j] = null;

When the string starts with a delimiter, index i is 0, so line[i-1] is undefined. Calling undefined.includes(...) throws an unhandled TypeError. Furthermore, calling .includes('\n', '\r') with two string arguments treats '\r' as the numeric index parameter rather than a secondary character check.

Expected Behavior

The csv node should correctly parse CSV strings starting with a delimiter by assigning null to the first column (when i === 0), without throwing a TypeError.

Steps To Reproduce

Add a csv node configured in Legacy mode (default CSV spec).
Pass a payload starting with a delimiter / empty first column, e.g.: ",1,2,3\n".
Observe that Node-RED throws TypeError: Cannot read properties of undefined (reading 'includes') at line 233.

Example flow

json

[
    {
        "id": "tab_csv_bug_repro",
        "type": "tab",
        "label": "Repro: CSV Delimiter TypeError",
        "disabled": false,
        "info": ""
    },
    {
        "id": "inject_csv_data",
        "type": "inject",
        "z": "tab_csv_bug_repro",
        "name": "Send CSV with empty first col",
        "props": [
            {
                "p": "payload",
                "v": ",1,2,3\n",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "x": 190,
        "y": 140,
        "wires": [
            [
                "csv_parser_node"
            ]
        ]
    },
    {
        "id": "csv_parser_node",
        "type": "csv",
        "z": "tab_csv_bug_repro",
        "name": "CSV Parser (Legacy Mode)",
        "sep": ",",
        "hdrin": false,
        "hdrout": "none",
        "multi": "one",
        "ret": "\\n",
        "temp": "a,b,c,d",
        "skip": "0",
        "strings": true,
        "include_empty_strings": false,
        "include_null_values": true,
        "spec": "legacy",
        "x": 490,
        "y": 140,
        "wires": [
            [
                "debug_csv_out"
            ]
        ]
    },
    {
        "id": "debug_csv_out",
        "type": "debug",
        "z": "tab_csv_bug_repro",
        "name": "Output",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "payload",
        "targetType": "msg",
        "statusVal": "",
        "statusType": "auto",
        "x": 750,
        "y": 140,
        "wires": []
    }
]

Environment

Node-RED version: 5.0.6 (and earlier)
Node.js version: v18.x / v20.x / v22.x / v24.x
npm version: 10.x / 11.x
Platform/OS: Windows / Linux / macOS
Browser: N/A (Core parser node)

Source: node-red/node-red

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