jQuery 如果值介于两个数字之间
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if value is between two numbers
提问by Inigo
I want to be able to test whether a value is within a number range. This is my jQuery code...
我希望能够测试一个值是否在一个数字范围内。这是我的jQuery代码...
if ((year < 2099) && (year > 1990)){
return 'good stuff';
}
Is there a simpler way to do this in jQuery? For example, is there something like this...
在 jQuery 中有没有更简单的方法来做到这一点？例如，有没有这样的...
if (1990 < year < 2099){
return 'good stuff';
}
回答by Mark Rushakoff
In many languages, the second way will be evaluated from left to right incorrectly with regard to what you want.
在许多语言中，第二种方式会根据您想要的东西从左到右错误地进行评估。
In C, for instance, 1990 < yearwill evaluate to 0 or 1, which then becomes 1 < 2099, which is always true, of course.
例如，在 C 中，1990 < year将计算为 0 或 1，然后变为1 < 2099，当然，这始终为真。
Javascript is a quite similar to C: 1990 < yearreturns trueor false, and those boolean expressions seem to numerically compare equal to 0 and 1 respectively.
Javascript 与 C: 1990 < yearreturns trueor非常相似false，这些布尔表达式似乎在数字上分别等于 0 和 1。
But in C#, it won't even compile, giving you the error:
但在 C# 中，它甚至不会编译，给你错误：
error CS0019: Operator '<' cannot be applied to operands of type 'bool' and 'int'
错误 CS0019：运算符“<”不能应用于“bool”和“int”类型的操作数
You get a similar error from Ruby, while Haskell tells you that you cannot use <twice in the same infix expression.
你从 Ruby 得到一个类似的错误，而 Haskell 告诉你不能<在同一个中缀表达式中使用两次。
Off the top of my head, Python is the only language that I'm sure handles the "between" setup that way:
在我的脑海中，Python 是唯一一种我确定以这种方式处理“之间”设置的语言：
>>> year = 5
>>> 1990 < year < 2099
False
>>> year = 2000
>>> 1990 < year < 2099
True
The bottom line is that the first way (x < y && y < z)is always your safest bet.
最重要的是，第一种方式(x < y && y < z)始终是您最安全的选择。
回答by Max Sylvester
You could make your own method:
你可以制定自己的方法：
// jquery
$(function() {
var myNumber = 100;
try {
if (myNumber.isBetween(50, 150))
alert(myNumber + " is between 50 and 100.");
else
alert(myNumber + " is not between 50 and 100.");
} catch (e) {
alert(e.message());
}
});
// js prototype
if (typeof(Number.prototype.isBetween) === "undefined") {
Number.prototype.isBetween = function(min, max, notBoundaries) {
var between = false;
if (notBoundaries) {
if ((this < max) && (this > min)) between = true;
alert('notBoundaries');
} else {
if ((this <= max) && (this >= min)) between = true;
alert('Boundaries');
}
alert('here');
return between;
}
}
hope this helps.
希望这可以帮助。
Max
最大限度
回答by khalid
The fast and simple way to make this is to create a function like this:
实现这一点的快速而简单的方法是创建一个像这样的函数：
function inRange(n, nStart, nEnd)
{
if(n>=nStart && n<=nEnd) return true;
else return false;
}
Then use that as follows:
然后按如下方式使用它：
inRange(500, 200, 1000) => this return true;
Or like this:
或者像这样：
inRange(199, 200, 1000) => this return false;
回答by Allan Taylor
From a similar solution here: http://indisnip.wordpress.com/2010/08/26/quicktip-check-if-a-number-is-between-two-numbers/
从这里的类似解决方案：http: //indisnip.wordpress.com/2010/08/26/quicktip-check-if-a-number-is-between-two-numbers/
$.fn.between = function(a,b){
return (a < b ? this[0] >= a && this[0] <= b : this[0] >= b && this[0] <= a);
}
回答by dckrooney
If you don't like the boolean operator, you could always use nested if statements:
如果您不喜欢布尔运算符，您可以始终使用嵌套的 if 语句：
if (1990 < year)
{
if( year < 2099)
return 'good stuff';
}
