javascript - Cannot code prepend logger correctly -

i have simple function prepend desired string beginning of each line. have working streams, in cases it's convenient using console.log() type of construct.

here function:

// takes string prepend, , stream prepend to:

exports.lp = function (str, strm) {     return function prependlog() {         var args = array.from(arguments);         var hasnonwhitespace = args.some(function (a) {             var str = string(a);             return str.length > 0 && /\s/g.test(str);         });         if (hasnonwhitespace) {             strm.write(str);         }         args.foreach(function (s, i) {             string(s).split('\n').foreach(function (s, i) {                 if (i < 1) {                     strm.write(s + ' ');                 }                 else {                     strm.write('\n' + str + s);                 }             });         });         strm.write('\n');     }; }; 

here use:

const {lp} = require('log-prepend'); const fn = lp(' [foobar] ', process.stdout);   fn('\n'); fn(); fn(); fn('','',''); fn('log1', 'log2\n3',4,5 + '\n55'); fn('a','b','c'); 

and here output above:

 [foobar]      [foobar] log1 log2   [foobar] 34 5   [foobar] 55  [foobar] b c  

the problem empty lines no non-whitespace character, works, when include newline character, outputs [foobar] though there nothing on line.

i can't figure out why function doesn't omit [foobar] lines no non-whitespace. exact, first instance of [foobar] above mystifying me.

having little trouble following logic here because expecting use index variable first foreach function, when it's using second? renaming initial variables might help.