JQuery/Javascript 和 && 运算符的使用
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JQuery/Javascript and the use of && operators
提问by mrEmpty
I'm trying to get a simple conditional statement to work, and running into problems. The failing code:
我试图让一个简单的条件语句起作用，但遇到了问题。失败的代码：
$(document).ready(function(){
var wwidth = $(window).width();
if (wwidth < 321) {
alert("I am 320 pixels wide, or less");
window.scrollTo(0,0);
} else if (wwidth > 321) && (wwidth < 481) {
alert("I am between 320 and 480 pixels wide")
}
});
If I remove the else if part of the code, I get the alert. If I try to use && or || operators it will fail. I've Googled, I can't find a reason why it's not working. I've also tried:
如果我删除代码的 else if 部分，我会收到警报。如果我尝试使用 && 或 || 运营商它会失败。我用谷歌搜索过，我找不到它不起作用的原因。我也试过：
((wwidth > 321 && wwidth < 481))
along with other ways, just in case it's some odd syntax thing.
以及其他方式，以防万一它是一些奇怪的语法事情。
Any help would be greatly appreciated. Thanks :)
任何帮助将不胜感激。谢谢 ：）
回答by Mikey
((wwidth > 321) && (wwidth < 481))
This is the condition you need (http://jsfiddle.net/malet/wLrpt/).
这是您需要的条件（http://jsfiddle.net/malet/wLrpt/）。
I would also consider making your conditions clearer like so:
我也会考虑让你的条件更清晰，如下所示：
if (wwidth <= 320) {
alert("I am 320 pixels wide, or less");
window.scrollTo(0,0);
} else if ((wwidth > 320) && (wwidth <= 480)) {
alert("I am between 320 and 480 pixels wide")
}
回答by Jonny Burger
if (wwidth > 321 && wwidth < 481) {
//do something
}
回答by ron tornambe
There are two issues. The first has already been answered, the second is "wwidth > 320" which should be "wwidth>=320". What if the window is larger than 480?
有两个问题。第一个已经得到回答，第二个是“wwidth > 320”，应该是“wwidth>=320”。如果窗口大于 480 怎么办？
you can also implement "between" as follows:
您还可以按如下方式实现“介于”：
Number.prototype.between = function(a, b) {
return this >= a && this <= b
}
$(document).ready(function(){
var wwidth = $(window).width();
if (wwidth < 321) {
alert("I am 320 pixels wide, or less");
window.scrollTo(0,0);
} else if (wwidth.between(321,481))
alert("I am between 320 and 480 pixels wide")
else alert("I am greater than 480 pixels wide.");
});
