js(1)

NAME

js - interpret, execute, and compile JavaScript files

SYNOPSIS

js [-acfghlNStvV] [-d  type]  [-e  code]  [-O[level]]  [-r
option] [-s size] [-W option] file [argument]...

DESCRIPTION

The js program is the JavaScript interpreter command. It

can be used to execute JavaScript and JavaScript byte-code files.

The progam can also be used to compile JavaScript files into the

byte-code files.

OPTIONS

-a, --annotate-assembler

Annotate the created assembler listing with the

original JavaScript source code. The option can be used only

with the --assembler option.

-c, --compile

Compile JavaScript files to byte-code. The gener

ated byte-code is saved to file which name is created from the

name of the input file by replacing the suffix .js with the suf

fix .jsc. The compilation can be controlled with options

--debug, --optimize, and --compiler-option.

-d type, --dispatch=type

Use the byte-code instruction dispatch method

type. The current implementation supports the following dispatch

methods:

switch-basic

The basic switch-method using a big

switch-case table to dispatch the instruction. This method is

available only if the interpreter has been configured with the

option --with-all-dispatchers.

switch An optimized version of the switch-method.

This method is supported on all environments.

jumps The fastest dispatch method that uses the

`computed goto' statement of the GNU C-compiler. This method is

available if the interpreter has been compiled with the GNU C

compiler.

The default dispatch method, for environments that has the

GNU C-compiler, is jumps. For all other environments, the de

fault method is switch.

-e code, --eval=code

Evaluate JavaScript code code.

-f, --file

Stop processing options and use the next argument

as the name of the JavaScript (or byte-code) file. All the re

maining arguments are passed to the interpreter through the ARGS

array. The first item of the array will be the name of the

script, i.e. the argument that follows the option --file.

-g, --debug

Make the compiler to generate debugging informa

tion to the generated byte-code files. This option can be used

with the option --compile.

-h, --help

Print a short help message that describes the op

tions that can be given to the js program.

-l, --load

Load multiple JavaScript and JavaScript byte-code

files to the interpreter. Normally, the first non-option argu

ment is evaluated and all remaining arguments are passed to the

script as arguments. With the option --load, multiple files can

be loaded the to the interpreter. The loading can be stopped

with option --file that specifies the last file to load.

-N, --no-compiler

Do not define the compiler to the virtual machine.

This option makes the interpreter smaller, but the interpreter

can only execute pre-compiled byte-code files. The option dis

ables the eval global method.

-O [level], --optimize[=level]

Set the compiler optimization level to level. The

compiler has three different optimization levels:

0 Do not optimize.

1 Perform all cheap optimizations which do

not required heavy assembler instruction analyzing.

2 Perform all optimizations, supported by

the compiler.

The default optimization level is 1.

-r option, --secure=option

Turn on virtual machine security option option.

The following security options are available:

file Disable insecure methods from the buit-in

File object.

system Disable insecure methods from the buit-in

System object.

-s size, --stack-size=size

Set the size of the virtual machine operand stack

to size. The size of the virtual machine operand stack is set at

the startup-time and it can't be enlarged dynamically at the run

time.

-S, --assembler

Compile JavaScript files to JavaScript assembler.

The generated assembler listing is saved to file which name is

created from the name of the input file by replacing the suffix

.js with the suffix .jas. The compilation can be controlled with

options --optimize, and --compiler-option.

-t, --stacktrace

Print a stack trace on error. When an error oc

curs during the evaluation of a script, the virtual machine will

halt and the js program terminates. If the option --stacktrace

was given to the interpreter, the virtual machine will print a

stack trace that shows the call stack at the point of the error.

-v, --verbose

Increase the verbosity of the interpreter. The

option can be given multiple times to increase the amount of mes

sages the interpreter prints.

-V, --version

Print the version number of the js program.

-W option, --compiler-option=option

Set JavaScript compiler options according to the

option specification option. The specification option can be

given in two forms. In the normal form, the option specifies a

compiler option that should be set on. If the specification

@var{option} starts with the prefix `no-', the specified option

will be turn off. The following option specifications are cur

rently implemented:

all match most of the compile time options

pedantic

match all compile time options. This op

tion generates as much warnings as possible. It will also com

plain about some things that are allowed by the ECMAScript stan

dard, but which are consired to show bad programming style, for

example, missing semicolons.

runtime match all runtime options

shadow warn if a variable declaration shadows a

parameter

undefined

runtime check for undefined global vari

ables

unused-argument

warn about unused arguments

unused-variable

warn about unused local variables

with-clobber

warn if the with-lookup of a symbol is

clobbered because the symbol is defined to be a local variable or

a function argument

missing-semicolon

warn about missing semicolons that are

fixed by the missing semicolon inserting during the compilation

strict-ecma

warn about things that are supported by

this implementation, but are not allowed by the ECMAScript stan

dard. These features are:

- line terminators in string and regular

expression constant

deprecated

warn if deprecated features has been used

in the source code

-x, --executable

Add execute permissions to the generated byte-code

files. This option is useful on Linux environments where

JavaScript byte-code files can be executed natively with the

`binfmt_js' module.

AUTHOR

Markku Rossi <mtr@ngs.fi>

NGS JavaScript WWW home page: <http://www.ngs.fi/js/>

SEE ALSO

jsdas(1)

JS Sep 25, 1998

JS(1)