CODEWITHSUNDEEP
javascriptjsonnode.jsecmascript-6
jet miller
jet miller

Reputation: 275

How to parse a Map to json with ecma6 (typescript) in node.js

with the following code i got an error in app.js using node 5.1 and typescript 6.1.2

the file i am trying to parse is a bookmark.json from firefox. my goal is to parse it to a map, to work with it and parse it back to json.

   'use strict';
    declare function require(name:string);
    let fs = require('fs');

    fs.readFile( './bookmarks.json', 'utf8', handleFile );

    function handleFile( err, data ) {

        function strMapToObj(strMap) {
            let obj = Object.create(null);
            for (let [k,v] of strMap) {
                obj[k] = v;
            }
            return obj;
        }
        function strMapToJson(strMap) {
            return JSON.stringify(strMapToObj(strMap));
        }

        function objToStrMap(obj) {
            let strMap = new Map();
            for (let k of Object.keys(obj)) {
                strMap.set(k, obj[k]);
            }
            return strMap;
        }    
        function jsonToStrMap(jsonStr) {
            return objToStrMap(JSON.parse(jsonStr));
        }

        if(err) throw err;

        let myMap = jsonToStrMap(JSON.parse(JSON.stringify(data)));
        console.log(myMap); // works well
        let result = strMapToJson(myMap);
        console.log(result); // returns an error       
    }

i got an syntax error with an unexpected token for (let [k, v] of strMap)

how to fix it?

how to parse such a map from firefox bookmarks.json back to json?

Upvotes: 1

Views: 1029

Answers (1)

jet miller
jet miller

Reputation: 275

ok, here is my solution: i use the json8 library from https://github.com/JSON8/JSON8

'use strict';

declare function require(name:string);
let fs = require('fs');
let oo = require('json8');


fs.readFile( './bookmarks.json', 'utf8', handleFile );

function handleFile( err, data ) {

    function mapToJson(map) {
        return oo.serialize(map);
    }

    function objToStrMap(obj) {
        let strMap = new Map();
        for (let k of Object.keys(obj)) {
            strMap.set(k, obj[k]);
        }
        return strMap;
    }


    function jsonToStrMap(jsonStr) {
        return objToStrMap(JSON.parse(jsonStr));
    }


    if(err) throw err;

    let myMap = jsonToStrMap(JSON.parse(JSON.stringify(data)));
    //console.log(myMap);

    let result = mapToJson(myMap);
    console.log(result); // gives the correct object back

}

Upvotes: 1

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