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npm · #1277 most downloaded on npm
In-memory file-system with Node's fs API.
Last release 5 days ago
29 Sep 2026
Ships fairly regularly
a new release about every 2 weeks
Nearly every release is documented
notes for 57 of the last 60 stable releases
2 versions withdrawn
withdrawn after publishing
11 years old
267 releases · first in 2015
'fromJSON()' did not consider cwd when creating directories
deps: update dependency fs-monkey to v1.0.1
One column per quarter.
should throw EEXIST instead of EISDIR on mkdirSync('/')
deps: update dependency fs-monkey to v1
replace fast-extend with native Object.assign
export DirectoryJSON from index
remove space from error message
🐛 handle opening directories with O_DIRECTORY (acdfac8), closes #494
rmdir: proper async functionality
watch: trigger change event for creation/deletion of children in a folder
## 3.0.1 (2019-11-26) ### Performance Improvements * ⚡️ bump fast-extend
TCallback to accept null for error parameter (aedcbda)Link#walk to return Link | null (1b76cb1)children in Link to be possibly undefined (b4945c2)_modeToNumber to be called w/ undefined (07c0b7a)_modeToNumber to return undefined (3e3c992)assertEncoding to be called w/ undefined (e37ab9a)Dirent~build to accept undefined for the encoding parameter (8ca3550)flagsToNumber to be called w/ undefined (dbfc754)mkdtempBase to be called w/ undefined for encoding (f28c395)modeToNumber to be called w/ undefined (336821d)realpathBase to be called w/ undefined for encoding (e855f1c)tryGetChild util function (b5093a1)tryGetChildNode util function (62b5a52)Volume.releasedFds array (9e21f3a)null to ._link property in FSWatcher (71569c0)null to ._steps property in FSWatcher (0e94b9c)null to .buf property in Node (00be0c2)null to .link property in File (5d01713)null to .node property in File (d06201e)null to .node property in Link (4d7f439)null to .parent property in Link (b3e60b6)null to .symlink property in Node (9bfb6f5)null to StatWatcher.prev property (fd1a253)null to StatWatcher.vol property (1540522)#vol or #parent of link to null (b396f04)strictNullChecks (3896de7)StatWatcher.timeoutRef property optional (d09cd03)#access to be compatible w/ strictNullChecks (82ed81b)#copyFileSync to be compatible w/ strictNullChecks (40f8337)#createLink to be compatible w/ strictNullChecks (7d8559d)#ftruncate to be compatible w/ strictNullChecks (f2ea3f1)#mkdir to be compatible w/ strictNullChecks (d5d7883)#mkdirp to be compatible w/ strictNullChecks (6cf0bce)#mkdtempBase to be compatible w/ strictNullChecks (d935b3b)#mkdtempSync to be compatible w/ strictNullChecks (7e22617)#newFdNumber to be compatible w/ strictNullChecks (0bc4a15)#newInoNumber to be compatible w/ strictNullChecks (e9ba56c)#openFile to be compatible w/ strictNullChecks (1c4a4ba)#openLink to be compatible w/ strictNullChecks (216a85f)#read to be compatible w/ strictNullChecks (87b587f)#readdirBase to be compatible w/ strictNullChecks (ab248b4)#readFileBase to be compatible w/ strictNullChecks (27a4dad)#readlinkBase to be compatible w/ strictNullChecks (b2e0f76)#resolveSymlinks to be compatible w/ strictNullChecks (6dc4913)#statBase to be compatible w/ strictNullChecks (ba0c20a)#symlink to be compatible w/ strictNullChecks (4148ad3)#truncate to be compatible w/ strictNullChecks (fadbd77)#watch to be compatible w/ strictNullChecks (415a186)#watchFile to be compatible w/ strictNullChecks (2c02287)#write to be compatible w/ strictNullChecks (2ba6e0f)#writeFile to be compatible w/ strictNullChecks (ac78c50)#writeFileBase to be compatible w/ strictNullChecks (e931778)#writeSync to be compatible w/ strictNullChecks (7b67eea)copyFile tests to be compatible w/ strictNullChecks (e318af2)errors to be compatible w/ strictNullChecks (b25c035)exists tests to be compatible w/ strictNullChecks (81a564f)renameSync tests to use tryGetChildNode (8cd782a)volume tests to be compatible w/ strictNullChecks (f02fbac)volume tests to use tryGetChild (5a6624f)volume tests to use tryGetChildNode (34acaac)writeFileSync tests to be compatible w/ strictNullChecks (4b7f164)getArgAndCb function (f8bb0f8)throwError fn w/ inline throw createError() calls (c9a0fd6)🐛 adjust definition of TCallback to accept null for error parameter
TCallback to accept null for error parameter (aedcbda)Link#walk to return Link | null (1b76cb1)children in Link to be possibly undefined (b4945c2)_modeToNumber to be called w/ undefined (07c0b7a)_modeToNumber to return undefined (3e3c992)assertEncoding to be called w/ undefined (e37ab9a)Dirent~build to accept undefined for the encoding parameter (8ca3550)flagsToNumber to be called w/ undefined (dbfc754)mkdtempBase to be called w/ undefined for encoding (f28c395)modeToNumber to be called w/ undefined (336821d)realpathBase to be called w/ undefined for encoding (e855f1c)tryGetChild util function (b5093a1)tryGetChildNode util function (62b5a52)Volume.releasedFds array (9e21f3a)null to ._link property in FSWatcher (71569c0)null to ._steps property in FSWatcher (0e94b9c)null to .buf property in Node (00be0c2)null to .link property in File (5d01713)null to .node property in File (d06201e)null to .node property in Link (4d7f439)null to .parent property in Link (b3e60b6)null to .symlink property in Node (9bfb6f5)null to StatWatcher.prev property (fd1a253)null to StatWatcher.vol property (1540522)#vol or #parent of link to null (b396f04)strictNullChecks (3896de7)StatWatcher.timeoutRef property optional (d09cd03)#access to be compatible w/ strictNullChecks (82ed81b)#copyFileSync to be compatible w/ strictNullChecks (40f8337)#createLink to be compatible w/ strictNullChecks (7d8559d)#ftruncate to be compatible w/ strictNullChecks (f2ea3f1)#mkdir to be compatible w/ strictNullChecks (d5d7883)#mkdirp to be compatible w/ strictNullChecks (6cf0bce)#mkdtempBase to be compatible w/ strictNullChecks (d935b3b)#mkdtempSync to be compatible w/ strictNullChecks (7e22617)#newFdNumber to be compatible w/ strictNullChecks (0bc4a15)#newInoNumber to be compatible w/ strictNullChecks (e9ba56c)#openFile to be compatible w/ strictNullChecks (1c4a4ba)#openLink to be compatible w/ strictNullChecks (216a85f)#read to be compatible w/ strictNullChecks (87b587f)#readdirBase to be compatible w/ strictNullChecks (ab248b4)#readFileBase to be compatible w/ strictNullChecks (27a4dad)#readlinkBase to be compatible w/ strictNullChecks (b2e0f76)#resolveSymlinks to be compatible w/ strictNullChecks (6dc4913)#statBase to be compatible w/ strictNullChecks (ba0c20a)#symlink to be compatible w/ strictNullChecks (4148ad3)#truncate to be compatible w/ strictNullChecks (fadbd77)#watch to be compatible w/ strictNullChecks (415a186)#watchFile to be compatible w/ strictNullChecks (2c02287)#write to be compatible w/ strictNullChecks (2ba6e0f)#writeFile to be compatible w/ strictNullChecks (ac78c50)#writeFileBase to be compatible w/ strictNullChecks (e931778)#writeSync to be compatible w/ strictNullChecks (7b67eea)copyFile tests to be compatible w/ strictNullChecks (e318af2)errors to be compatible w/ strictNullChecks (b25c035)exists tests to be compatible w/ strictNullChecks (81a564f)renameSync tests to use tryGetChildNode (8cd782a)volume tests to be compatible w/ strictNullChecks (f02fbac)volume tests to use tryGetChild (5a6624f)volume tests to use tryGetChildNode (34acaac)writeFileSync tests to be compatible w/ strictNullChecks (4b7f164)getArgAndCb function (f8bb0f8)throwError fn w/ inline throw createError() calls (c9a0fd6)set-up semantic-release packages
# 2.17.0 (2019-11-26) ### Features * release v2.17 (c4bc372) * release v2.17.0 (try 2)
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## 2.15.5 (2019-07-16) ### Bug Fixes * check for process (8b9b00c) * check for process
🐛 accept null as value in fromJSON functions
🐛 mocks process.emitWarning for browser compatibility (e3456b2), closes #374
## 2.15.2 (2019-02-16) ### Bug Fixes * 🐛 BigInt type handling
🐛 show directory path when throwing EISDIR in mkdir
volume: add env variable to suppress fs.promise api warnings
fds to start from 0x7fffffff instead of 0xffffffff
don't copy legacy files into dist (ab8ffbb), closes #263
# 2.14.0 (2018-11-12) ### Features * add bigint option support
🐛 don't install semantic-release, incompat with old Node
add missing string type for realpathSync's options argument
add missing string type for appendFile's options argument
add withFileTypes option support for readdir and readdirSync
add relative option support for mkdir and mkdirSync
## 2.10.1 (2018-09-28) ### Bug Fixes * add setImmediate.bind
# 2.10.0 (2018-09-16) ### Features * trigger minor release
## 2.9.4 (2018-07-05) ### Bug Fixes * release #174 fix
## 2.9.3 (2018-07-05) ### Bug Fixes * remove unused buggy import
## 2.9.2 (2018-07-05) ### Bug Fixes * trigger release on Travis
## 2.9.1 (2018-06-26) ### Bug Fixes * check if .destroy exists
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deps: update dependency fs-monkey to ^0.3.0
fs.open on directory as read-only
correct error for writeFileSync and non-existing path
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