Javascript添加无法正常工作 [英] Javascript Addition wont work
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问题描述
有人可以告诉我如何将这些变量加起来:
can anybody tell me how to add up these variables:
var preciopag = document.valores.T1.value;
var libras = document.valores.T2.value;
var serviciocom = 5.00
var contador1 = 0;
var contador2 = 0;
var tramite = 0;
var enviopty = 0;
var ITBMS = 0;
var Total = preciopag + serviciocom + enviopty + tramite + ITBMS;
预先感谢。
推荐答案
元素的值
始终是字符串,因此 +
将导致串联,而不是加法。
The value
of elements is always a string, so +
will result in concatenation, not addition.
在检索值时将字符串转换为数字:
Convert from string to number when retrieving the values:
var preciopag = +document.valores.T1.value;
var libras = +document.valores.T2.value;
我曾经用过 +
将查看整个字符串,但您可能会看到 parseFloat
,它将在最后忽略任何无效的内容;
There I've used +
, which will look at the entire string, but you might look at parseFloat
which will ignore anything invalid at the end; it depends entirely on what you want to do with semi-valid input.
演示:
var preciopag = "5"; // Simulating document.valores.T1.value
var libras = "10"; // Simulating document.valores.T2.value
var serviciocom = 5.00
var contador1 = 0;
var contador2 = 0;
var tramite = 0;
var enviopty = 0;
var ITBMS = 0;
var Total = preciopag + serviciocom + enviopty + tramite + ITBMS;
snippet.log(Total); // "55000" - wrong
// Instead:
preciopag = +"5"; // Simulating document.valores.T1.value
libras = +"10"; // Simulating document.valores.T2.value
Total = preciopag + serviciocom + enviopty + tramite + ITBMS;
snippet.log(Total); // "10" - right
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
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