Question

我正在使用 localstorage 在其中存储数据并在构造函数中从中进行检索，我希望检查变量保留在刷新页面时的值比较其值为0，在获得更新值后，如果check == 0则应该进入功能。

我坚持认为这是可能的吗？

check=0;

ngOnInit() { 

    if(this.check==0)
    {
        this.list =new Array();
        this.list.push("Purchase a ring for my beautiful wife","get new GALAXY Note 150","Complete kevin's work ASAP","Buy 2 dozen eggs","Get milk on my way to home");
        localStorage.setItem('list', JSON.stringify(this.list));
        this.check++;
        localStorage.setItem('incre', JSON.stringify(this.check));
    }

    this.check=JSON.parse( localStorage.getItem('incre'));
    this.list=JSON.parse( localStorage.getItem('list'));
}

Answer 1

从constructor删除所有内容。

public check: number = 0;

ngOnInit() {
this.check = JSON.parse(localStorage.getItem('incre')) || 0;


if (this.check === 0) {
 // do the rest
}

}

Answer 2

如果我正确理解了您的问题，那么this.check=JSON.parse( localStorage.getItem('incre'));应位于构造函数的顶部，然后您应该在if

中进行比较

试试这个

check=0;
list = any[];

constructor() { 

 this.check=JSON.parse( localStorage.getItem('incre'));    
 if(this.check == undefined || this.check==0)
 {
  this.list =new Array();
  this.list.push("Purchase a ring for my beautiful wife","get new GALAXY Note 150","Complete kevin's work ASAP","Buy 2 dozen eggs","Get milk on my way to home");
  localStorage.setItem('list', JSON.stringify(this.list));
  this.check++;
  localStorage.setItem('incre', JSON.stringify(this.check));
 }

  this.list=JSON.parse( localStorage.getItem('list'));
}

Answer 3

将此语句移至构造函数的开头

＆＃13;

constructor() { 
   this.check=JSON.parse(localStorage.getItem('incre'));
   if(this.check==0)

＆＃13;

Answer 4

你甚至没有像dr.nio的代码那样设置initital 0。

public check: number = 0;
ngOnInit() {
  this.check = JSON.parse(localStorage.getItem('incre'))
  if (!this.check) {}

}

清晰可读。

从Angular 4中的ngOnInit中的localstorage获取数据，但它在刷新时重置其值

4 个答案: