[@types/node] 3x properties on process.stdout & process.stderr should be marked "?" (optional/undefined): .columns + .rows + .isTTY

[hi2u]

Location:

DefinitelyTyped/types/node/tty.d.ts

Lines 187 to 203 in 41aa59f

	/**
	* A `number` specifying the number of columns the TTY currently has. This property
	* is updated whenever the `'resize'` event is emitted.
	* @since v0.7.7
	*/
	columns: number;
	/**
	* A `number` specifying the number of rows the TTY currently has. This property
	* is updated whenever the `'resize'` event is emitted.
	* @since v0.7.7
	*/
	rows: number;
	/**
	* A `boolean` that is always `true`.
	* @since v0.5.8
	*/
	isTTY: boolean;

• Those 3 properties are all undefined when Node isn't running on an interactive terminal, e.g. in all these situations:
  • When piping Node's output into a file > /tmp/output.txt or another process | less
  • Running inside a cron job
  • Running as a systemd service
  • etc...

Some testing code:

console.table(
    ['columns', 'rows', 'isTTY'].map((key) => {
        return {
            property: `process.stdout.${key}`,
            value: process.stdout[key],
            typeof: typeof process.stdout[key],
            in: key in process.stdout,
            hasOwn: Object.hasOwn(process.stdout, key),
            hasOwnProperty: Object.prototype.hasOwnProperty.call(process.stdout, key),
            propertyIsEnumerable: Object.prototype.propertyIsEnumerable.call(process.stdout, key),
        };
    }),
);

✔️ If you run the code above in a regular interactive terminal, all is good, you get something like...

┌─────────┬──────────────────────────┬───────┬───────────┬──────┬────────┬────────────────┬──────────────────────┐
│ (index) │         property         │ value │  typeof   │  in  │ hasOwn │ hasOwnProperty │ propertyIsEnumerable │
├─────────┼──────────────────────────┼───────┼───────────┼──────┼────────┼────────────────┼──────────────────────┤
│    0    │ 'process.stdout.columns' │  211  │ 'number'  │ true │  true  │      true      │         true         │
│    1    │  'process.stdout.rows'   │  59   │ 'number'  │ true │  true  │      true      │         true         │
│    2    │  'process.stdout.isTTY'  │ true  │ 'boolean' │ true │ false  │     false      │        false         │
└─────────┴──────────────────────────┴───────┴───────────┴──────┴────────┴────────────────┴──────────────────────┘

❌ If it's not an interactive terminal, all 3 of those properties are undefined:

┌─────────┬──────────────────────────┬───────────┬─────────────┬───────┬────────┬────────────────┬──────────────────────┐
│ (index) │         property         │   value   │   typeof    │  in   │ hasOwn │ hasOwnProperty │ propertyIsEnumerable │
├─────────┼──────────────────────────┼───────────┼─────────────┼───────┼────────┼────────────────┼──────────────────────┤
│    0    │ 'process.stdout.columns' │ undefined │ 'undefined' │ false │ false  │     false      │        false         │
│    1    │  'process.stdout.rows'   │ undefined │ 'undefined' │ false │ false  │     false      │        false         │
│    2    │  'process.stdout.isTTY'  │ undefined │ 'undefined' │ false │ false  │     false      │        false         │
└─────────┴──────────────────────────┴───────────┴─────────────┴───────┴────────┴────────────────┴──────────────────────┘

So the types should be optional:

columns?: number;
rows?: number;
isTTY?: boolean;

• Applies to both process.stdout + process.stderr

Missing methods

Additionally, the .getWindowSize() + .hasColors() methods (and probably more) don't even exist when non-interactive...

✔️ Interactive output:

echo "console.log(process.stdout.getWindowSize()); console.log(process.stdout.hasColors());" | node

[ 211, 59 ]
true

🔥 Non-interactive will throw exceptions:

echo "console.log(process.stdout.getWindowSize())" | node | cat ; echo "console.log(process.stdout.hasColors())" | node | cat

TypeError: process.stdout.getWindowSize is not a function
TypeError: process.stdout.hasColors is not a function

[typescript-bot]

Thanks for the discussion about "node", some useful links for everyone:

• npm
• DT
• Related discussions

Pinging the DT module owners: @microsoft, @jkomyno, @alvis, @r3nya, @btoueg, @smac89, @Touffy, @DeividasBakanas, @eyqs, @Hannes-Magnusson-CK, @hoo29, @kjin, @ajafff, @islishude, @mwiktorczyk, @mohsen1, @galkin, @parambirs, @eps1lon, @ThomasdenH, @WilcoBakker, @wwwy3y3, @samuela, @kuehlein, @bhongy, @chyzwar, @trivikr, @yoursunny, @qwelias, @ExE-Boss, @peterblazejewicz, @addaleax, @victorperin, @ZYSzys, @nodejs, @LinusU, @wafuwafu13, @mcollina, @Semigradsky.

[hi2u]

Here's a quick bash shell command you can run to see the non-interactive output piped through cat:

echo -e "console.table([" \
        "'columns', 'rows', 'isTTY'].map((key) => {" \
            "return {" \
                "property: \`process.stdout.\${key}\`," \
                "value: process.stdout[key]," \
                "typeof: typeof process.stdout[key]," \
                "in: key in process.stdout," \
                "hasOwn: Object.hasOwn(process.stdout, key)," \
                "hasOwnProperty: Object.prototype.hasOwnProperty.call(process.stdout, key)," \
                "propertyIsEnumerable: Object.prototype.propertyIsEnumerable.call(process.stdout, key)," \
            "};" \
        "})," \
    ");" \
    | node | cat

Remove the | cat part from the end to compare with interactive.

[ghost]

See :

• process.stdout.isTTY is undefined when git-bash (on Windows) invokes node via a shell script nodejs/node#39673