为什么更改一个属性（对象）也会在另一个单独声明的属性中发生变化？

Question

我有2个这样声明的属性：ngOnInit() {this.defaultRequirements = myData.property1.countryDocument; //should never changethis.filteredRequirements = myData.property1.countryDocument; }当我运行此onFilter函数时，defaultRequirements属性也会发生突变。onFilter(selectedSections) {    let index = -1;    this.defaultRequirements.forEach(country => {      index++;      const filteredSectionsList = [];      country.section.forEach(section => {        selectedSections.value.forEach(selectedSelection => {          const selection = selectedSelection.split(/\s*[-]\s*/);            if (country.countryCode === selection[0]) {            console.log('matched');            filteredSectionsList.push(section);          }        });        const countryObj = Object.assign({}, country, {          section: [...filteredSectionsList]        })// Here is the issue, when filtering, this.defaultRequirements also gets changed!        this.filteredRequirements[index] = countryObj;      })    })}问题我不明白如何对this.filteredRequirements进行突变也对this.defaultRequirements进行突变（它们都等同于同一件事）！如何避免这种行为并使defaultRequirements不受filteredRequirements上所做更改的影响？

Answer 1

试试这个：

ngOnInit() {

    this.defaultRequirements = JSON.parse(JSON.stringify(myData.property1.countryDocument));   

    this.filteredRequirements = JSON.parse(JSON.stringify(myData.property1.countryDocument));

}

或者

ngOnInit() {

    this.defaultRequirements = {...myData.property1.countryDocument}

    this.filteredRequirements = {...myData.property1.countryDocument}

}