csv - Using Typescript unable to assign a value to the Class level variable inside fs.createReadStream -


i new typescript , have scenario in need read data csv file , assign values class level map<> variable. following code trying out facing below issues:-

a) vs code intellisence doesn't prompt me name of class level map<> variable when try this.nameofmapvariable inside fs.createreadstream function

b) if ignore intellisence thingy , try , write code assigning value, @ runtime error:-

cannot read property set of undefined

code snippet of csvhelper.ts file:-

import * csvparse 'csv-parser'; import fs = require('fs'); var parse = csvparse.parser;  export class csvhelper {   public testspecificdata = new map<string, string>();    public fetchtestspecificdata(clsname: string, mthdname: string): map<string, string> {     fs.createreadstream('../testdata/testspecificdata.csv').pipe(csvparse()).on('data', function (data) {       if (data.testclass == clsname && data.testmethod == mthdname)         this.testspecificdata.set(data.key.tostring(), data.value.tostring());      }     )         return this.testspecificdata;    } }

thats because defining function, called event data. keyword this gets new context call, testspecificdata indeed not exist.

you can try lambda expression, this stays in expected context:

fs.createreadstream('../testdatatestspecificdata.csv')     .pipe(csvparse())     .on('data', (data) => {        if (data.testclass == clsname && data.testmethod == mthdname) {            this.testspecificdata.set(data.key.tostring(), data.value.tostring());        }      });

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