jQuery中的简单数学 [英] Simple math in jquery

问题描述

我正在读取一个选择表单值，并在jquery中将其乘以50.在每次乘以50之前，我需要在选择菜单返回的数量上加上1.令人反感的代码如下所示.

I am reading a select form value and multiplying it by 50 in jquery. I need to add a value of 1 to the qty that is returned by the select menu every time before multiplying by 50. How would I do that? The offending code looks like this.

 $('#selectform').val() *50);

如果我使用

 $('#selectform').val() +1 *50);

结果不正确.

推荐答案

应使用括号.

 ($('#selectform').val()*1 + 1) *50;

您当前的表达式解释为:

Your current expression is interpreted as:

 var something = $('#selectform').val();
 var another   = 1 * 50;
 var result    = something + another

.val()之后的*1用于将字符串值转换为数字.如果省略，则表达式将解释为:

The *1 after .val() is used to convert the string value to a number. If it's omitted, the expression will be interpreted as:

var something = $('#selectform').val() + "1";  //String operation
var result    = something * 50;    // something is converted to a number, and
                                   //    multiplied by 50

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