1.3 的值在 parsefloat 中变为 1.40000001

Question

我正在从 mongodb 中读取一些值，然后我有一些可以提高价格的选项。有 2 种类型的选项单一和多个。 if single 所有操作运行顺利。如果在我读取值时有多个（例如“1.3”）解析 float returns 1.4000001 执行此操作的代码如下：

 this.item.productPrice = parseFloat(this.item.productPrice) - 
   parseFloat(a.price);

和

          this.item.productPrice = parseFloat(this.item.productPrice) + parseFloat(a.price);

using debugger at the beginning of the line item.productPrice is 1.3 but after the parsing it become 1.4000001 and adds the a.price

完整代码块

//this one takes the selection and adds it to selectedparams array
  selected(ev: any) {
    debugger;
    const a = JSON.parse(ev);
    if (a.multiple) {
      if (Array.isArray(this.selectedparams[a.paramName])) {
        const va = !a.value;
        const index = this.objectinArray(this.selectedparams[a.paramName], {
          option: a.option,
          price: a.price,
          value: va
        });
        if (index !== -1) {
          this.item.productPrice = parseFloat(this.item.productPrice) - parseFloat(a.price);
          this.selectedparams[a.paramName].splice(index, 1);
          this.zone.run(() => {});
        } else {
          this.selectedparams[a.paramName].push({ option: a.option, price: a.price, value: a.value });
          this.item.productPrice = parseFloat(this.item.productPrice) + parseFloat(a.price);
          this.zone.run(() => {});
        }
      } else {
        this.selectedparams[a.paramName] = [];
        this.selectedparams[a.paramName].push({ option: a.option, price: a.price, value: a.value });
        this.item.productPrice = this.item.productPrice + parseFloat(a.price);
        console.log('hereeeeeeeeeeeeeeeee', this.item.productPrice);
        this.zone.run(() => {});
      }

    } else {
      this.selectedparams[a.paramName] = { selected: a.selected, price: a.price };
    }
    this.calcPrice();
  }

//this one dows the calculation after adding
  calcPrice() {
    const keys = Object.keys(this.selectedparams);
    console.log(this.item);
    let newprice = this.item.productPrice;
    keys.forEach(el => {
      if (Array.isArray(this.selectedparams[el])) {
        this.selectedparams[el].forEach((i: any) => {
          newprice = newprice + parseFloat(i.price);
        });
      } else {
        newprice = newprice + parseFloat(this.selectedparams[el].price);
      }
    });
    this.showPrice = newprice;
  }

Answer 1

TLDR(math behind) - You could use the .toFixed()函数：

var result = parseFloat('0.1') + parseFloat('1.3');
console.log(result.toFixed(1)); // 1.4

var result = parseFloat('0.1') + parseFloat('1.3');
console.log(result); // 1.400000001

1.3 的值在 parsefloat 中变为 1.40000001

value of 1.3 is becoming 1.40000001 in parsefloat

angular

typescript

numbers

parsefloat