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util: if present, fallback to toString using the %s formatter

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This makes sure that `util.format` uses `String` to stringify an object
in case the object has an own property named `toString` with type
`function`. That way objects that do not have such function are still
inspected using `util.inspect` and the old behavior is preserved as
well.

PR-URL: https://github.com/nodejs/node/pull/27621
Refs: https://github.com/facebook/jest/issues/8443
Reviewed-By: Roman Reiss <me@silverwind.io>
This commit is contained in:
Ruben Bridgewater 2019-05-09 09:22:15 +02:00
parent 182b48aa77
commit 5518664d41
No known key found for this signature in database
GPG Key ID: F07496B3EB3C1762
3 changed files with 55 additions and 12 deletions
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6
doc/api/util.md
View File

@ -221,9 +221,9 @@ specifiers. Each specifier is replaced with the converted value from the
corresponding argument. Supported specifiers are:
* `%s` - `String` will be used to convert all values except `BigInt`, `Object`
and `-0`. `BigInt` values will be represented with an `n` and Objects are
inspected using `util.inspect()` with options
`{ depth: 0, colors: false, compact: 3 }`.
and `-0`. `BigInt` values will be represented with an `n` and Objects that
have no user defined `toString` function are inspected using `util.inspect()`
with options `{ depth: 0, colors: false, compact: 3 }`.
* `%d` - `Number` will be used to convert all values except `BigInt` and
`Symbol`.
* `%i` - `parseInt(value, 10)` is used for all values except `BigInt` and

39
lib/internal/util/inspect.js
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@ -93,6 +93,10 @@ const { NativeModule } = require('internal/bootstrap/loaders');
let hexSlice;
const builtInObjects = new Set(
Object.getOwnPropertyNames(global).filter((e) => /^([A-Z][a-z]+)+$/.test(e))
);
const inspectDefaultOptions = Object.seal({
showHidden: false,
depth: 2,
@ -1541,16 +1545,33 @@ function formatWithOptions(inspectOptions, ...args) {
switch (nextChar) {
case 115: // 's'
const tempArg = args[++a];
if (typeof tempArg !== 'string' &&
typeof tempArg !== 'function') {
tempStr = inspect(tempArg, {
...inspectOptions,
compact: 3,
colors: false,
depth: 0
});
if (typeof tempArg === 'number') {
tempStr = formatNumber(stylizeNoColor, tempArg);
// eslint-disable-next-line valid-typeof
} else if (typeof tempArg === 'bigint') {
tempStr = `${tempArg}n`;
} else {
tempStr = String(tempArg);
let constr;
if (typeof tempArg !== 'object' ||
tempArg === null ||
typeof tempArg.toString === 'function' &&
// A direct own property.
(hasOwnProperty(tempArg, 'toString') ||
// A direct own property on the constructor prototype in
// case the constructor is not an built-in object.
(constr = tempArg.constructor) &&
!builtInObjects.has(constr.name) &&
constr.prototype &&
hasOwnProperty(constr.prototype, 'toString'))) {
tempStr = String(tempArg);
} else {
tempStr = inspect(tempArg, {
...inspectOptions,
compact: 3,
colors: false,
depth: 0
});
}
}
break;
case 106: // 'j'

22
test/parallel/test-util-format.js
View File

@ -138,8 +138,30 @@ assert.strictEqual(util.format('%s', 42n), '42n');
assert.strictEqual(util.format('%s', Symbol('foo')), 'Symbol(foo)');
assert.strictEqual(util.format('%s', true), 'true');
assert.strictEqual(util.format('%s', { a: [1, 2, 3] }), '{ a: [Array] }');
assert.strictEqual(util.format('%s', { toString() { return 'Foo'; } }), 'Foo');
assert.strictEqual(util.format('%s', { toString: 5 }), '{ toString: 5 }');
assert.strictEqual(util.format('%s', () => 5), '() => 5');
// String format specifier including `toString` properties on the prototype.
{
class Foo { toString() { return 'Bar'; } }
assert.strictEqual(util.format('%s', new Foo()), 'Bar');
assert.strictEqual(
util.format('%s', Object.setPrototypeOf(new Foo(), null)),
'[Foo: null prototype] {}'
);
global.Foo = Foo;
assert.strictEqual(util.format('%s', new Foo()), 'Bar');
delete global.Foo;
class Bar { abc = true; }
assert.strictEqual(util.format('%s', new Bar()), 'Bar { abc: true }');
class Foobar extends Array { aaa = true; }
assert.strictEqual(
util.format('%s', new Foobar(5)),
'Foobar [ <5 empty items>, aaa: true ]'
);
}
// JSON format specifier
assert.strictEqual(util.format('%j'), '%j');
assert.strictEqual(util.format('%j', 42), '42');