Typescript/javascript中的递归函数 [英] recursive functions in typescript/javascript

问题描述

我试图递归调用以下函数.

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;
  };

当我尝试调用该函数时，它显示一个错误无法读取未定义的属性'getData'.代码中是否有任何错误或执行此操作的任何其他方式.

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.

推荐答案

forEach 接受回调，它是一个匿名函数，匿名函数中的 this 指的是<在非严格模式下为code> window ，在严格模式下为 undefined .

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.

您需要绑定上下文:

  Object.keys(value).forEach(function (keydata) {
    let obj = value[keydata];
    this.getData(keydata,value[keydata]);

    console.log(key,obj,obj instanceof Object)
  }.bind(this));

或使用箭头功能:

  Object.keys(value).forEach((keydata) => {
    let obj = value[keydata];
    this.getData(keydata,value[keydata]);

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

或仅将指向 this 的指针作为 forEach 的第二个参数传递:

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);

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