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buffer: improve Buffer.from performance

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Using == null in code paths that are expected to mostly receive
objects, arrays or other more complex data types is not
ideal because typecasting these types is very slow. Change
to instead check === null || === undefined. Also move one
variable assignment in fromString after an if condition
that doesn't need it (and returns if truthy).

PR-URL: https://github.com/nodejs/node/pull/15178
Refs: https://jsperf.com/triple-equals-vs-double-equals/3
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
This commit is contained in:
Anatoli Papirovski 2017-09-04 08:53:43 -04:00 committed by Ruben Bridgewater
parent 16a81cd2c0
commit fc1fa4e2c4
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GPG Key ID: F07496B3EB3C1762
1 changed files with 3 additions and 3 deletions
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lib/buffer.js
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@ -193,7 +193,7 @@ Buffer.from = function from(value, encodingOrOffset, length) {
if (isAnyArrayBuffer(value)) if (isAnyArrayBuffer(value))
return fromArrayBuffer(value, encodingOrOffset, length); return fromArrayBuffer(value, encodingOrOffset, length);
if (value == null) { if (value === null || value === undefined) {
throw new errors.TypeError( throw new errors.TypeError(
'ERR_INVALID_ARG_TYPE', 'ERR_INVALID_ARG_TYPE',
'first argument', 'first argument',
@ -208,7 +208,7 @@ Buffer.from = function from(value, encodingOrOffset, length) {
); );
const valueOf = value.valueOf && value.valueOf(); const valueOf = value.valueOf && value.valueOf();
if (valueOf != null && valueOf !== value) if (valueOf !== null && valueOf !== undefined && valueOf !== value)
return Buffer.from(valueOf, encodingOrOffset, length); return Buffer.from(valueOf, encodingOrOffset, length);
var b = fromObject(value); var b = fromObject(value);
@ -322,9 +322,9 @@ function allocate(size) {
function fromString(string, encoding) { function fromString(string, encoding) {
var length; var length;
if (typeof encoding !== 'string' || encoding.length === 0) { if (typeof encoding !== 'string' || encoding.length === 0) {
encoding = 'utf8';
if (string.length === 0) if (string.length === 0)
return new FastBuffer(); return new FastBuffer();
encoding = 'utf8';
length = byteLengthUtf8(string); length = byteLengthUtf8(string);
} else { } else {
length = byteLength(string, encoding, true); length = byteLength(string, encoding, true);