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doc: small fixes in the buffer.md #9795
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Original file line number | Diff line number | Diff line change |
---|---|---|
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@@ -282,7 +282,7 @@ const buf = Buffer.from([1, 2, 3]); | |
// 1 | ||
// 2 | ||
// 3 | ||
for (var b of buf) { | ||
for (const b of buf) { | ||
console.log(b); | ||
} | ||
``` | ||
|
@@ -404,14 +404,14 @@ to initialize a `Buffer` to zeroes. | |
Example: | ||
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```js | ||
const buf = new Buffer(5); | ||
const buf = new Buffer(10); | ||
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// Prints: (contents may vary): <Buffer 78 e0 82 02 01> | ||
// Prints: (contents may vary): <Buffer 48 21 4b 00 00 00 00 00 30 dd> | ||
console.log(buf); | ||
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buf.fill(0); | ||
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// Prints: <Buffer 00 00 00 00 00> | ||
// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00> | ||
console.log(buf); | ||
``` | ||
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|
@@ -523,14 +523,14 @@ initialized*. The contents of the newly created `Buffer` are unknown and | |
Example: | ||
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```js | ||
const buf = Buffer.allocUnsafe(5); | ||
const buf = Buffer.allocUnsafe(10); | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. ditto |
||
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// Prints: (contents may vary): <Buffer 78 e0 82 02 01> | ||
// Prints: (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32> | ||
console.log(buf); | ||
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buf.fill(0); | ||
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// Prints: <Buffer 00 00 00 00 00> | ||
// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00> | ||
console.log(buf); | ||
``` | ||
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|
@@ -995,7 +995,7 @@ overlapping region within the same `Buffer` | |
```js | ||
const buf = Buffer.allocUnsafe(26); | ||
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for (var i = 0 ; i < 26 ; i++) { | ||
for (let i = 0 ; i < 26 ; i++) { | ||
// 97 is the decimal ASCII value for 'a' | ||
buf[i] = i + 97; | ||
} | ||
|
@@ -1028,7 +1028,7 @@ const buf = Buffer.from('buffer'); | |
// [3, 102] | ||
// [4, 101] | ||
// [5, 114] | ||
for (var pair of buf.entries()) { | ||
for (const pair of buf.entries()) { | ||
console.log(pair); | ||
} | ||
``` | ||
|
@@ -1122,7 +1122,7 @@ Examples: | |
const buf = Buffer.from('this is a buffer'); | ||
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// Prints: 0 | ||
console.log(buf.indexOf('this'))); | ||
console.log(buf.indexOf('this')); | ||
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// Prints: 2 | ||
console.log(buf.indexOf('is')); | ||
|
@@ -1212,7 +1212,7 @@ const buf = Buffer.from('buffer'); | |
// 3 | ||
// 4 | ||
// 5 | ||
for (var key of buf.keys()) { | ||
for (const key of buf.keys()) { | ||
console.log(key); | ||
} | ||
``` | ||
|
@@ -1223,8 +1223,8 @@ added: v6.0.0 | |
--> | ||
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* `value` {String | Buffer | Integer} What to search for | ||
* `byteOffset` {Integer} Where to begin searching in `buf` (not inclusive). | ||
**Default:** [`buf.length`] | ||
* `byteOffset` {Integer} Where to begin searching in `buf`. | ||
**Default:** [`buf.length`]` - 1` | ||
* `encoding` {String} If `value` is a string, this is its encoding. | ||
**Default:** `'utf8'` | ||
* Returns: {Integer} The index of the last occurrence of `value` in `buf` or `-1` | ||
|
@@ -1264,7 +1264,7 @@ console.log(buf.lastIndexOf('buffer', 4)); | |
const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2'); | ||
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// Prints: 6 | ||
console.log(utf16Buffer.lastIndexOf('\u03a3', null, 'ucs2')); | ||
console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'ucs2')); | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Both null and undefined are technically not valid arguments. Maybe make a better example? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. @silverwind It is a bit complicated here and I hoped it would be fixed fully when #9801 is addressed. Maybe this could be postponed till that big issue fixed? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Yeah fine with me. |
||
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// Prints: 4 | ||
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'ucs2')); | ||
|
@@ -1302,7 +1302,7 @@ use [`buf.slice()`] to create a new `Buffer`. | |
Examples: | ||
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```js | ||
var buf = Buffer.allocUnsafe(10); | ||
let buf = Buffer.allocUnsafe(10); | ||
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buf.write('abcdefghj', 0, 'ascii'); | ||
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@@ -1446,7 +1446,7 @@ const buf = Buffer.from([0, 5]); | |
console.log(buf.readInt16BE()); | ||
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// Prints: 1280 | ||
console.log(buf.readInt16LE(1)); | ||
console.log(buf.readInt16LE()); | ||
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// Throws an exception: RangeError: Index out of range | ||
console.log(buf.readInt16LE(1)); | ||
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@@ -1509,10 +1509,10 @@ Examples: | |
```js | ||
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]); | ||
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// Prints: 1234567890ab | ||
// Prints: -546f87a9cbee | ||
console.log(buf.readIntLE(0, 6).toString(16)); | ||
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// Prints: -546f87a9cbee | ||
// Prints: 1234567890ab | ||
console.log(buf.readIntBE(0, 6).toString(16)); | ||
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// Throws an exception: RangeError: Index out of range | ||
|
@@ -1673,7 +1673,7 @@ one byte from the original `Buffer` | |
```js | ||
const buf1 = Buffer.allocUnsafe(26); | ||
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for (var i = 0 ; i < 26 ; i++) { | ||
for (let i = 0 ; i < 26 ; i++) { | ||
// 97 is the decimal ASCII value for 'a' | ||
buf1[i] = i + 97; | ||
} | ||
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@@ -1737,7 +1737,7 @@ console.log(buf1); | |
const buf2 = Buffer.from([0x1, 0x2, 0x3]); | ||
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// Throws an exception: RangeError: Buffer size must be a multiple of 16-bits | ||
buf2.swap32(); | ||
buf2.swap16(); | ||
``` | ||
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### buf.swap32() | ||
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@@ -1822,7 +1822,7 @@ Examples: | |
```js | ||
const buf1 = Buffer.allocUnsafe(26); | ||
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for (var i = 0 ; i < 26 ; i++) { | ||
for (let i = 0 ; i < 26 ; i++) { | ||
// 97 is the decimal ASCII value for 'a' | ||
buf1[i] = i + 97; | ||
} | ||
|
@@ -1897,7 +1897,7 @@ const buf = Buffer.from('buffer'); | |
// 102 | ||
// 101 | ||
// 114 | ||
for (var value of buf.values()) { | ||
for (const value of buf.values()) { | ||
console.log(value); | ||
} | ||
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@@ -1908,7 +1908,7 @@ for (var value of buf.values()) { | |
// 102 | ||
// 101 | ||
// 114 | ||
for (var value of buf) { | ||
for (const value of buf) { | ||
console.log(value); | ||
} | ||
``` | ||
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@@ -2293,7 +2293,7 @@ Returns the maximum number of bytes that will be returned when | |
`buf.inspect()` is called. This can be overridden by user modules. See | ||
[`util.inspect()`] for more details on `buf.inspect()` behavior. | ||
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Note that this is a property on the `buffer` module as returned by | ||
Note that this is a property on the `buffer` module returned by | ||
`require('buffer')`, not on the `Buffer` global or a `Buffer` instance. | ||
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## buffer.kMaxLength | ||
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@@ -2306,6 +2306,9 @@ added: v3.0.0 | |
On 32-bit architectures, this value is `(2^30)-1` (~1GB). | ||
On 64-bit architectures, this value is `(2^31)-1` (~2GB). | ||
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Note that this is a property on the `buffer` module returned by | ||
`require('buffer')`, not on the `Buffer` global or a `Buffer` instance. | ||
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## buffer.transcode(source, fromEnc, toEnc) | ||
<!-- YAML | ||
added: v7.1.0 | ||
|
@@ -2325,6 +2328,8 @@ The transcoding process will use substitution characters if a given byte | |
sequence cannot be adequately represented in the target encoding. For instance: | ||
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```js | ||
const buffer = require('buffer'); | ||
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const newBuf = buffer.transcode(Buffer.from('€'), 'utf8', 'ascii'); | ||
console.log(newBuf.toString('ascii')); | ||
// Prints: '?' | ||
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@@ -2333,6 +2338,9 @@ console.log(newBuf.toString('ascii')); | |
Because the Euro (`€`) sign is not representable in US-ASCII, it is replaced | ||
with `?` in the transcoded `Buffer`. | ||
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Note that this is a property on the `buffer` module returned by | ||
`require('buffer')`, not on the `Buffer` global or a `Buffer` instance. | ||
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## Class: SlowBuffer | ||
<!-- YAML | ||
deprecated: v6.0.0 | ||
|
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how is this a fix? why is
10
better than5
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See #9786. This increases the example size (with the predicted outputs in the comments) so the output could not be confusing if the example is testing via a file.
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Scanned #9876, not finding what you mean. And further confused by "testing via a file". There is no file in this example. PR should standalone, can you describe why this is an improvement?
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Sorry for my incomprehensibility. Consider this case: a user copies this example, pastes it in the empty file
test.js
, saves it and runs via console or IDE to see the output. He will not see the described output, he will see two identical lines with null bytes all the times. In #9786 I've described the cause. This fix increases the size of possibletest.js
so the two lines will be different. I'll try to make some GIFs now to explain more clearly what I mean.There was a problem hiding this comment.
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In the first GIF you can see a test attempt with the old code example. See how both output lines are the same in contravention of the doc prediction.
In the second GIF you can see a test attempt with the new code example. See how both output lines are different as the doc predicts.
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I guess I don't mind the buffer getting a bit bigger, but if you are hoping that means it will always be non-zero.... I don't think that's true. Your own system proves that the initial values can be anything, right?
10
bytes is not special, AFAICT.There was a problem hiding this comment.
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Thus I think the docs should make the behaviour clear, not the examples. Examples show only one scenario, the docs say how it will be for all scenarios. And frankly, I don't get the point of this example, it doesn't add anything to my understanding. The docs already said the memory wouldn't be initialized. But that's another issue, I guess.
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"Contents may vary" does mean it can be anything, including zeroed, but in my case, it is always all zeroes. I do not mean it is true for all the systems, but my case shows that for some systems it is. If the output is all zeroes one time and is not all zeroes another time, it would be OK. But persistent zeroes is confusing, it can make a novice think that doc is wrong.
In the #9786 I've linked to stats that show my system not always zero buffers 8 bytes or smaller. It has some correlation between script size and buffer zeroing scheme. Maybe I have a unique situation. But it seems we won't get more stats because I can't make my point clear(
So what should I do? Just not change these fragments?
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I don't know. It clearly confused you, and docs should clarify, not confuse. On the other hand, 10 seems as random as 5. I guess leave it, at least anyone wondering why it was changed can find the PR, this conversation, and understand why it changed.
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Thank you for the patience.
So can I remake the PR as I've described below?