Question

我试图将两个数字相乘并添加另一个数字，但输出显示为NaN。怎么解决这个问题？

这是我的代码

medicines = [new Medicine()];

this.sum = 0;// sum also type of number

for (let i = 0; i < this.medicines.length; i++)
{
    this.sum = this.sum + this.medicines[i].price * this.medicines[i].quantity;//here price and quantity of type number
    console.log(typeof this.sum);//but this print NaN
}

药物模型

export class Medicine{
   constructor(){}
   name: String;
   quantity:number;
   price:number
}

Answer 1

应该是这样的：

medicines:Medicine[]=[{name: 'name', quantity:3, price:6},{name: 'name', quantity:3, price:6},{name: 'name', quantity:3, price:6}]

或：

medicines: Array<Medicine> = new Array<Medicine>();

Answer 2

你可以这样做吗

this.sum = this.sum + +this.medicines[i].price * +this.medicines[i].quantity;

将+放在属性之前，因此如果它不是数字，它会将您的属性值转换为数字。

Answer 3

medicines: [] = new Medicine();

this.sum = 0;// sum also type of number
for (let i = 0; i < this.medicines.length; i++)
{
    this.sum = this.sum + this.medicines[i].price * this.medicines[i].quantity;//here price and quantity of type number
    console.log(typeof this.sum);//but this print NaN
}

在Angular 5中输出两个数字的NaN

3 个答案: