传递角6中功能中的参数

Question

import { Component, OnInit } from '@angular/core';
@Component({
 selector: 'app-calculator',
 templateUrl: './calculator.component.html',
 styleUrls: ['./calculator.component.css']
})
export class CalculatorComponent implements OnInit {
  public result:number=0;
  public num:number=0;
  public final:number=0;
  constructor() { }
  ngOnInit() {
  }
  onClick(e){
    this.num = Number(e.target.value);
    this.result = this.num+this.result;
    if(e.target.value == "="){
      console.log(this.result); // the output of console here is : null
      this.display();
    } 
  }
  display(){
      console.log(this.result); // here the console output is : NaN
      this.final = this.result;
  }
}

html

<div>
  <input type="number" value="{{result}}"><br><br>
  <button value="1" (click)="onClick($event)">1</button>&nbsp;&nbsp;
  <button value="2" (click)="onClick($event)">2</button>&nbsp;&nbsp;
  <button value="=" (click)="onClick($event)">=</button><br><br>
  Result : {{final}}
</div>

我想将结果打印在显示功能中，但没有这样做。即使在onclick（）函数中，if语句中的结果也不可划分。我想将结果打印在显示功能

Answer 1

this.num = Number(e.target.value);//Suppose e.target.value is '='

您不能将=符号转换为数字，否则您将获得NAN

您的代码应如下

onClick(e){
  if(e.target.value == "="){
    console.log(this.result);
    this.display();
  }
 else{
  this.num = Number(e.target.value);
  this.result = this.num+this.result;
  }
}

Answer 2

尝试更改OnClick方法中的顺序以避免NAN检验。当您尝试将" ="转换为数字时，您将获得NAN。

onClick(e){
    if(e.target.value == "="){
      console.log(this.result); // the output of console here is : null
      this.display();
    } else {
      this.num = Number(e.target.value);
      this.result = this.num+this.result;
    }
  }

这是一个stackblitz

Answer 3

您应该在OnClick函数中检查if(!isNaN(e.target.value))。

import { Component } from '@angular/core';
@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
   public result:number=0;
  public num:number=0;
  public final:number=0;
  constructor() { }
  ngOnInit() {
  }
  onClick(e){
    if(!isNaN(e.target.value)){
    this.num = Number(e.target.value);
    this.result = this.num+this.result;
    }
    if(e.target.value == "="){
      console.log(this.result); // the output of console here is : null
      this.display();
    } 
  }
  display(){
      console.log(this.result); // here the console output is : NaN
      this.final = this.result;
  }
}

https://stackblitz.com/edit/angular-add

Answer 4

您是否应该这样的条件：

onClick(e){
if(e.target.value !=='='){
  this.num = Number(e.target.value);
  this.result = this.num+this.result;
}else{
  console.log(this.result);
  this.display();
}    }     

您可以从：stackblitz.com