uglify js error unexpected token eof "undefined"

Question

So I installed npm using npm install uglify-js

I run a command which is:

cat file1.js file2.js .. fileN.js | uglifyjs -o files.min.js

and I get this error:

WARN: ERROR: Unexpected token eof «undefined», expected punc «,» [-:630,15]

/usr/local/lib/node_modules/uglify-js/lib/parse.js:199
    throw new JS_Parse_Error(message, line, col, pos);
          ^
Error
    at new JS_Parse_Error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:185:18)
    at js_error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:199:11)
    at croak (/usr/local/lib/node_modules/uglify-js/lib/parse.js:630:9)
    at token_error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:638:9)
    at expect_token (/usr/local/lib/node_modules/uglify-js/lib/parse.js:651:9)
    at expect (/usr/local/lib/node_modules/uglify-js/lib/parse.js:654:36)
    at ctor.argnames (/usr/local/lib/node_modules/uglify-js/lib/parse.js:897:52)
    at function_ (/usr/local/lib/node_modules/uglify-js/lib/parse.js:902:15)
    at expr_atom (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1114:24)
    at maybe_unary (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1278:19)

Any ideas on what this is about or how I should go about fixing it?

Answer 1

ERROR: Unexpected token eof «undefined», expected punc «,» [-:630,15]

I believe all it means is that you are missing a , somewhere in your JS code, possibly on line 630, near character 15.

So if you concatenate the source of all your JS files, and take a look at line 630, you might find where the parser thought there was a missing comma.