Javascript 在javascript中计算百分比
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Calculate percentage in javascript
提问by John
I am trying to calculate in javascript. Some parts of the calculation are not working.
我正在尝试用 javascript 计算。计算的某些部分不起作用。
I want to calculate the total price with discount. For example: When price = 10.00 And discount = 50 (%)
我想用折扣计算总价。例如：当价格 = 10.00 且折扣 = 50 (%)
I need to calculate: 10.00 * 0,50
我需要计算：10.00 * 0,50
So I need something like this:
所以我需要这样的东西：
var totalValue = numVal1 / 0, numVal2
When I do this, the script is not working. How can I fix this?
当我这样做时，脚本不起作用。我怎样才能解决这个问题？
This is my full code:
这是我的完整代码：
function getPrice() {
var numVal1 = Number(document.getElementById("price").value);
var numVal2 = Number(document.getElementById("discount").value);
var totalValue = numVal1 / numVal2
document.getElementById("total").value = totalValue.toFixed(2);
}
回答by Jér?me
So you have a price ( 10 ) and a discount ( 50 )
所以你有一个价格（ 10 ）和一个折扣（ 50 ）
FinalPrice = price * ( 100-discount / 100 ) = 10 * ( 100-50 / 100 ) = 10 * 0.5 = 10 * 50%
FinalPrice = 价格 * ( 100-discount / 100 ) = 10 * ( 100-50 / 100 ) = 10 * 0.5 = 10 * 50%
So
所以
function getPrice() {
var numVal1 = Number(document.getElementById("price").value);
var numVal2 = Number(document.getElementById("discount").value);
var totalValue = numVal1 * ( (100-numVal2) / 100 )
document.getElementById("total").value = totalValue.toFixed(2);
}
回答by Camilo Andres Mu?oz Bravo
I think that you are not calculating adecually the value, it should be:
我认为你不是在计算价值，它应该是：
var totalValue = numVal1 *(numVal2/100);
回答by LoremIpsum
You can't expect JavaScript to understand that 0, numVal2is supposed to be inferred to a floating number. The comma has its own meaning in JavaScript. Instead, you should treat numVal2as a percentage (which it is) and do :
你不能指望 JavaScript 理解0, numVal2应该被推断为一个浮点数。逗号在 JavaScript 中有自己的含义。相反，您应该将其numVal2视为百分比（它是）并执行以下操作：
var totalValue = numVal1 / (numVal2 / 100);
回答by Andrew Bone
To make it a percent you'd divided the discount by 100 and multiplied it by the price.
要使其成为百分比，您可以将折扣除以 100 再乘以价格。
For example I bought some shoes, ￡50 is the normal price but it was a closing down sale so 75% off. so we need to work out 75% of 50 and then take that off.
例如我买了一些鞋子，￡50 是正常价格，但这是一个关闭销售所以 75% 的折扣。所以我们需要计算出 50 的 75%，然后把它去掉。
50 - (50 * 75 / 100) or 50 - (50 * 0.75)
50 - (50 * 75 / 100) 或 50 - (50 * 0.75)
(The shoes were only ￡12.50... bargain!)
（鞋子只要￡12.50...便宜货！）
I would go for something like:
我会去做类似的事情：
getPrice = function() {
var numVal1 = Number(document.getElementById("price").value);
var numVal2 = Number(document.getElementById("discount").value) / 100;
var totalValue = numVal1 - (numVal1 * numVal2)
document.getElementById("total").value = totalValue.toFixed(2);
}<input id="price">
<br>
<input id="discount">%
<br>
<button onclick="getPrice()">
Get total
</button>
<br>
<input readonly id="total">