How can I check JavaScript code for syntax errors ONLY from the command line?

Question

JavaScript programs can be checked for errors in IDEs or using online web apps but I'm looking for a way to detect syntax errors alone.

I've tried JSLint and JSHint and looked at their options but I haven't been able to find a combination that would exclude warnings and just shows the syntax errors.

How do I check JavaScript code for syntax errors only from the command line?

Answer 1

The solution is to enable jshint's --verbose option, which shows the error or warning code (e.g. E020 for Expected '}' to match '{' or W110 for Mixed double and single quotes), then grep for errors only:

jshint --verbose test.js | grep -E E[0-9]+.$

Answer 2

I use acorn:

$ acorn --silent tests/files/js-error.js; echo $?
Unexpected token (1:14)
1

$ acorn --silent tests/files/js-ok.js; echo $?
0

Install via: npm -g install acorn.

Answer 3

JSHint does what you want. http://www.jshint.com/

You can configure which warnings or errors to show.

An example:

$ jshint myfile.js
myfile.js: line 10, col 39, Octal literals are not allowed in strict mode.

1 error

Answer 4

Any JavaScript parser should do, acorn mentioned by @cweise is nice because it is fast and has a --silent switch.

You could also use esvalidate from the npm esprima package: http://ariya.ofilabs.com/2012/10/javascript-validator-with-esprima.html

$ npm install -g esprima
$ esvalidate js-file-with-errors.js 
js-file-with-errors.js:1: Invalid left-hand side in assignment

Answer 5

You could use node's built-in syntax checking option:

node --check filename.js

Ref: https://nodejs.org/api/cli.html#cli_c_check

Answer 6

Here is an answer for a Continuous Integration scenario.

1- Checks all the JavaScript files with exclude folder, subfolder and file features.

2- Exit if there is an error.

esvalidate --version || npm install -g esprima;
find ./ -not \( -path ./exclude_folder_1 -prune \) -not \( -path ./exclude/sub_folder -prune \) -not \( -path ./exclude/sub_folder_2 -prune \) ! -name exclude_specified_file.js  -name \*.js -exec esvalidate '{}' \; | grep -v "No syntax errors detected" && echo "Javascript Syntax error(s) detected" && exit 1;