Question

151

recursive functions in typescript/javascript

rated 0 times [ 153] [ 2] / answers: 1 / hits: 19602 / 7 Years ago, wed, april 19, 2017, 12:00:00

I am trying to call the following function recursively.

 public  getData(key,value){



   this.htmlString += '<span style=color:cornflowerblue>'+key+' </span>:';



    if(value instanceof Object){

      Object.keys(value).forEach(function (keydata) {

        let obj = value[keydata];

        this.getData(keydata,value[keydata]);



        console.log(key,obj,obj instanceof Object)

      });

    }else{

      this.htmlString += '<span>'+value+'</span>';

    }

    return this.htmlString;

  };

when i tried to call teh function it was showing an error Cannot read property 'getData' of undefined. Is there any wrong in the code or any other way to do this.

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devane

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4 Years ago

answered 7 Years ago marisela · Accepted Answer

forEach accepts a callback, which is an anonymous function, and this inside anonymous function refers to window in non-strict mode or undefined in strict mode.

You need to bind context:

  Object.keys(value).forEach(function (keydata) {

    let obj = value[keydata];

    this.getData(keydata,value[keydata]);



    console.log(key,obj,obj instanceof Object)

  }.bind(this));

or use an arrow function:

  Object.keys(value).forEach((keydata) => {

    let obj = value[keydata];

    this.getData(keydata,value[keydata]);



    console.log(key,obj,obj instanceof Object)

  });

or simply pass pointer to this as a second argument to forEach:

  Object.keys(value).forEach(function (keydata) {

    let obj = value[keydata];

    this.getData(keydata,value[keydata]);



    console.log(key,obj,obj instanceof Object)

  }, this);