Javascript scoping for object -

i in javascript object, how possible declare 1 variable in 1 scope; mean merely variable , start using object assigning properties "inside" other functions. how scoping case work?

https://github.com/ariya/esprima/blob/master/esprima.js

in code, extra variable declared without being given properties:

var token,     extra; 

and starts being used object follows:

function addcomment(type, value, start, end, loc) {     var comment, attacher;      assert(typeof start === 'number', 'comment must have valid position');      // because way actual token scanned, comments     // (if any) skipped twice during lexical analysis.     // thus, need skip adding comment if comment array     // handled it.     if (state.lastcommentstart >= start) {         return;     }     state.lastcommentstart = start;      comment = {         type: type,         value: value     };     if (extra.range) {         comment.range = [start, end];     }     if (extra.loc) {         comment.loc = loc;     }     extra.comments.push(comment);      if (extra.attachcomment) {         attacher = {             comment: comment,             leading: null,             trailing: null,             range: [start, end]         };         extra.pendingcomments.push(attacher);     } } 

the closest example can initiated object following function:

function tokenize(code, options) {     var tostring,         token,         tokens;      tostring = string;     if (typeof code !== 'string' && !(code instanceof string)) {         code = tostring(code);     }      delegate = syntaxtreedelegate;     source = code;     index = 0;     linenumber = (source.length > 0) ? 1 : 0;     linestart = 0;     length = source.length;     lookahead = null;     state = {         allowin: true,         labelset: {},         infunctionbody: false,         initeration: false,         inswitch: false,         lastcommentstart: -1     };      = {};      // options matching.     options = options || {};      // of course collect tokens here.     options.tokens = true;     extra.tokens = [];     extra.tokenize = true;     // following 2 fields necessary compute regex tokens.     extra.openparentoken = -1;     extra.opencurlytoken = -1;      extra.range = (typeof options.range === 'boolean') && options.range;     extra.loc = (typeof options.loc === 'boolean') && options.loc;      if (typeof options.comment === 'boolean' && options.comment) {         extra.comments = [];     }     if (typeof options.tolerant === 'boolean' && options.tolerant) {         extra.errors = [];     }      if (length > 0) {         if (typeof source[0] === 'undefined') {             // try first convert string. fast path             // old ie understands string indexing string             // literals , not string object.             if (code instanceof string) {                 source = code.valueof();             }         }     }      try {         peek();         if (lookahead.type === token.eof) {             return extra.tokens;         }          token = lex();         while (lookahead.type !== token.eof) {             try {                 token = lex();             } catch (lexerror) {                 token = lookahead;                 if (extra.errors) {                     extra.errors.push(lexerror);                     // have break on first error                     // avoid infinite loops.                     break;                 } else {                     throw lexerror;                 }             }         }          filtertokenlocation();         tokens = extra.tokens;         if (typeof extra.comments !== 'undefined') {             tokens.comments = extra.comments;         }         if (typeof extra.errors !== 'undefined') {             tokens.errors = extra.errors;         }     } catch (e) {         throw e;     } {         = {};     }     return tokens; } 

but still inside function, not in same scope

var token,     extra; 

how possible declare variable , instantiate properties inside function? how shared between different scopes? once given properties in 1 function, shared other scopes such scope in function? confusing.

line #3658 sets empty object:

extra = {};