clj -M -m cljs.main ...This guide requires ClojureScript 1.10.238 or later and assumes familiarity with the Quick Start.
The cljs.main namespace provides functions that allow ClojureScript programs
and interactive sessions to be launched via Java’s application launcher tool
java.
This guide is also easily used with any other Clojure build tool that
supports the Clojure CLI -m flag.
For example with clj:
clj -M -m cljs.main ...The cljs.main/main entry point accepts a variety of arguments and flags.
With no options or args, runs an interactive Read-Eval-Print Loop
init options:
-co, --compile-opts edn Options to configure the build, can be an EDN string or system-dependent path-separated list of EDN files / classpath resources. Options will be merged left to right.
-d, --output-dir path Set the output directory to use. If supplied, cljsc_opts.edn in that directory will be used to set ClojureScript compiler options
-re, --repl-env env The REPL environment to use. Built-in supported values: node, browser. Defaults to browser
-ro, --repl-opts edn Options to configure the repl-env, can be an EDN string or system-dependent path-separated list of EDN files / classpath resources. Options will be merged left to right.
-t, --target name The JavaScript target. Configures environment bootstrap and defaults to browser. Supported values: node or nodejs, webworker, none
init options only for --main and --repl:
-e, --eval string Evaluate expressions in string; print non-nil values
-i, --init path Load a file or resource
-v, --verbose bool If true, will enable ClojureScript verbose logging
init options only for --compile:
-O, --optimizations level Set optimization level, only effective with --compile main option. Valid values are: none, whitespace, simple, advanced
-o, --output-to file Set the output compiled file
-w, --watch path Continuously build, only effective with the --compile main option. Specifies a system-dependent path-separated list of directories to watch.
main options:
- Run a script from standard input
-c, --compile [ns] Run a compile. If optional namespace specified, use as the main entry point. If --repl follows, will launch a REPL after the compile completes. If --server follows, will start a web server that serves the current directory after the compile completes.
-h, --help, -? Print this help message and exit
-m, --main ns Call the -main function from a namespace with args
-r, --repl Run a repl
-s, --serve host:port Start a simple web server to serve the current directory
path Run a script from a file or resource
For --main and --repl:
Enters the cljs.user namespace
Binds *command-line-args* to a seq of strings containing command line args that appear after any main option
Runs all init options in order
Calls a -main function or runs a repl or script if requested
The init options may be repeated and mixed freely, but must appear before any main option.
In the case of --compile you may supply --repl or --serve options afterwards.
Paths may be absolute or relative in the filesystem or relative to
classpath. Classpath-relative paths have prefix of @ or @/
The same is also described in the usage message:
Usage: java -cp cljs.jar cljs.main [init-opt*] [main-opt] [arg*]
With no options or args, runs an interactive Read-Eval-Print Loop
init options:
-co, --compile-opts edn Options to configure the build, can be an EDN
string or system-dependent path-separated list of
EDN files / classpath resources. Options will be
merged left to right.
-d, --output-dir path Set the output directory to use. If supplied,
cljsc_opts.edn in that directory will be used to
set ClojureScript compiler options
-re, --repl-env env The REPL environment to use. Built-in supported
values: node, browser. Defaults to browser
-ro, --repl-opts edn Options to configure the repl-env, can be an EDN
string or system-dependent path-separated list of
EDN files / classpath resources. Options will be
merged left to right.
-t, --target name The JavaScript target. Configures environment
bootstrap and defaults to browser. Supported
values: node or nodejs, webworker, none
init options only for --main and --repl:
-e, --eval string Evaluate expressions in string; print non-nil
values
-i, --init path Load a file or resource
-v, --verbose bool If true, will enable ClojureScript verbose logging
init options only for --compile:
-O, --optimizations level Set optimization level, only effective with --
compile main option. Valid values are: none,
whitespace, simple, advanced
-o, --output-to file Set the output compiled file
-w, --watch paths Continuously build, only effective with the --
compile main option. Specifies a system-dependent
path-separated list of directories to watch.
main options:
- Run a script from standard input
-c, --compile [ns] Run a compile. If optional namespace specified,
use as the main entry point. If --repl follows,
will launch a REPL after the compile completes.
If --server follows, will start a web server that
serves the current directory after the compile
completes.
-h, --help, -? Print this help message and exit
-m, --main ns Call the -main function from a namespace with args
-r, --repl Run a repl
-s, --serve host:port Start a simple web server to serve the current
directory
path Run a script from a file or resource
For --main and --repl:
- Enters the cljs.user namespace
- Binds *command-line-args* to a seq of strings containing command line
args that appear after any main option
- Runs all init options in order
- Calls a -main function or runs a repl or script if requested
The init options may be repeated and mixed freely, but must appear before
any main option.
In the case of --compile you may supply --repl or --serve options afterwards.
Paths may be absolute or relative in the filesystem or relative to
classpath. Classpath-relative paths have prefix of @ or @/The simplest way to launch a ClojureScript repl is to use the following command line with the shipping cljs.jar:
java -cp cljs.jar cljs.mainThe REPL prompt shows the name of the current namespace, which defaults to cljs.user.
Several special vars are available when using the REPL:
*1, *2, *3 - hold the result of the last three expressions that were evaluated
*e - holds the result of the last exception.
To run a file full of ClojureScript code as a script, pass the path to the script to cljs.main as an argument:
java -cp cljs.jar cljs.main /path/to/myscript.cljsTo pass in arguments to a script, pass them in as further arguments when launching cljs.main:
java -cp cljs.jar cljs.main /path/to/myscript.cljs arg1 arg2 arg3The arguments will be provided to your program as a seq of strings bound to the var *command-line-args*:
*command-line-args* => ("arg1" "arg2" "arg3")To compile ClojureScript source code, pass the main namespace to cljs.main via the -c option:
java -cp src:cljs.jar cljs.main -c my-namespace.coreThe output will be written to the directory specified via the -d option (or out if unspecified), or to the file specified via the -o option.