typescript/javascript 中的递归函数
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recursive functions in typescript/javascript
提问by sravanthi
I am trying to call the following function recursively.
我正在尝试递归调用以下函数。
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.
当我尝试调用 teh 函数时，它显示错误“无法读取未定义的属性 'getData'。代码中是否有任何错误或以任何其他方式执行此操作。
回答by Max Koretskyi
forEachaccepts a callback, which is an anonymous function, and thisinside anonymous function refers to windowin non-strict mode or undefinedin strict mode.
forEach接受一个回调，它是一个匿名函数，匿名函数this内部是指window非严格模式或undefined严格模式。
You need to bind context:
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));
or use an arrow function:
或使用箭头函数：
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 thisas a second argument to forEach:
或者简单地将指针this作为第二个参数传递给forEach：
Object.keys(value).forEach(function (keydata) {
let obj = value[keydata];
this.getData(keydata,value[keydata]);
console.log(key,obj,obj instanceof Object)
}, this);
