npm-watch
v0.13.0
Published
run scripts from package.json when files change
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npm-watch
Run scripts from package.json when files change.
Common Issues
monorepo setups
: In a monorepo setup,npm-watch
may fail withENOENT
. The solution is to have nodemon globally installed. See here for more context
Synopsis
Install it:
npm install npm-watch
Add a top-level "watch"
config to your package.json
and a "watch" script to
your "scripts"
:
{
"watch": {
"test": "{src,test}/*.js"
},
"scripts": {
"test": "tape test/*.js",
"watch": "npm-watch"
}
}
There is the possibility to watch for different tasks
{
"watch": {
"run_android": {
"patterns": [
"app"
],
"extensions": "ts,html,scss",
"quiet": false
},
"run_ios": {
"patterns": [
"app"
],
"extensions": "ts,html,scss",
"quiet": false
}
},
"scripts": {
"watch_android": "npm-watch run_android",
"watch_ios": "npm-watch run_ios",
"run_android": "tns run android --emulator",
"run_ios": "tns run ios --emulator"
}
}
The top level keys of the "watch"
config should match the names of your "scripts"
, and
the values should be a glob pattern or array of glob patterns to watch.
Also it is now possible to obtain a second parameter to define the script which should be run for watching and not watch all possible scripts at once.
If you need to watch files with extensions other than those that nodemon
watches by default (.js
, .coffee
, .litcoffee
), you can set the value to an object with patterns
and extensions
keys. You can also add an ignore
key (a list or a string) to ignore specific files. Finally, you can add a quiet
flag to hide the script name in any output on stdout or stderr, or you can use the inherit
flag to preserve the original's process stdout or stderr. You can enable nodemon
legacy watch and specify the restart delay in milliseconds with the corresponding flags.
The
quiet
flag was changed from astring
to aboolean
in0.1.5
. Backwards compatibility will be kept for two patch versions.
Use runOnChangeOnly
to set the nodemon option --on-change-only. Setting this to true
tells nodemon to execute script on change only, not startup.
{
"watch": {
"test": {
"patterns": ["src", "test"],
"extensions": "js,jsx",
"ignore": "src/vendor/external.min.js",
"quiet": true,
"legacyWatch": true,
"delay": 2500,
"runOnChangeOnly": false
}
},
"scripts": {
"test": "tape test/*.js"
}
}
Start the watcher with npm run watch
in a terminal, then edit some files:
mkdir src test
npm run watch &
cat <<EOF > test/test-sum.js
var test = require('tape')
test('sum module', function (t) {
var sum = require('../src/sum.js')
t.ok(sum(1, 2), 3, "Sums appear correct")
t.end()
})
EOF
(Feel free to use the editor of your choice, cat
just makes for easy demos)
You should see that your tests ran automatically, and failed because src/sum.js
is missing. Let's fix that:
cat <<EOF > src/sum.js
module.exports = function (a, b) {
return 1
}
EOF
Our tests will run again, and this time they almost work. Let's fix sum.js
:
cat <<EOF > src/sum.js
module.exports = function (a, b) {
return a + b
}
EOF
Tests run perfectly, ship it to the enterprise!
Once you have the watcher running, you can force restart all tasks by entering rs
.
If you want to only force a single task, type the name of the key from the watch config (for example rs test
).
Global Config
setMaxListeners
If too many listeners are added to an event emitter, node.js
will send a warning (rightfully so) about potential memory leaks.
The default maximum is 10. If you need more than that, you can add a top level global config to your package.json
"watchGlobalConfig": {
"setMaxListeners": true
}
And max listeners will be set on the relevant processes to the minimum needed to avoid the warning.
Options
patterns
Array of paths to watch
"patterns": ["src", "test"]
extensions
Comma delimited list of file extensions to watch
"extensions": "js,jsx"
ignore
Add an ignore
property to your watch
object. The value of ignore
can be a string if you only want to ignore
a single glob:
"watch": {
"build": {
"ignore": "build",
...
}
...
}
Or an array if you want to ignore multiple globs:
"watch": {
"build": {
"ignore": [
"build",
"node_modules"
],
...
}
...
}
quiet
Boolean to hide the script name in any output on stdout and stderr
"quiet": false
inherit
Boolean to preserve the original process' stdout and stderr
"inherit": false
legacyWatch
Boolean to enable legacy watch
"legacyWatch": true
delay
Number of milliseconds to delay before checking for new files
"delay": 2500
clearBuffer
Boolean to clear the buffer after detecting a new change
"clearBuffer": true
verbose
Boolean to turn on the nodemons verbose mode
"verbose": true
silent
Boolean to turn on nodemons silent (quiet) mode Silent was used as we already had an existing flag called quiet. This may change in a future release
"silent": true
Acknowledgements
This module does very little but run nodemon
for you, all
credit for the reliable file watching and process restarting should go to there.
License
MIT