node js module to find a representation for a string with chemical elements

.gitignore

.idea/
*~
*.swp

package.json

{
  "name": "PSErep",
  "description": "A module for converting a word into a sequence of chemical element names",
  "version": "0.1.0"
}

PSErep.js

var elements = "H,He,Li,Be,B,C,N,O,F,Ne,L,Na,Mg,Al,Si,P,S,Cl,Ar,M,K,Ca,Sc,Ti,V."
    + "Cr,Mn,Fe,Co,Ni,Cu,Zn,Ga,Ge,As,Se,Br,Kr,Rb,Sr,Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag,"
    + "Cd,In,Sn,Sb,Te,I,Xe,Cs,Ba,Hf,Ta,W,Re,Os,Ir,Pt,Au,Hg,Tl,Pb,Bi,Po,At,Rn,Fr,"
    + "Ra,Rf,Db,Sg,Bh,Hs,Mt,Ds,Rg,Cn,Uut,Uuq,Uup,Uuh,Uus,Uuo,Q,La,Ce,Pr,Nd,Pm,"
    + "Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Ac,Th,Pa,U,Np,Pu,Am,Cm,Bk,Cf,Es,Fm,Md,No,Lr"
    .split(',');

function matcher(a) {
    var s = a.toLowerCase()
    return function(b) {
        return !s.indexOf(b.toLowerCase())}}

function flatten(a){
    if(!(a instanceof Array)) return [a]
    function rc(ar,el){
        return ar.concat(flatten(el)) }
    return a.reduce(rc, [])}

function build (str, finds) {
    if(str=="" || str==null) return finds
    var z = elements.filter(matcher(str)).map(function(match) {
        return flatten(build(str.slice(match.length), finds.concat([match])))})
    return z.length? z : finds }


// get PSE representations of a string
// @return an array of representations
exports.getRep = function(str) {
    return build(str, [])}

testChemElemRep.js

var c = require('./chemelemrep');

console.log( c.getRep('p') );
console.log( c.getRep('pb') );
console.log( c.getRep('pbr') );
console.log( c.getRep('asd') );
console.log( c.getRep('punk') );

There seems to be a typo at the end of line 1 of PSErep.js : [...]V_._"