javascript jquery 检查数字是否在列表中
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jquery check if number is in a list
提问by Anders
I have to check whether a variable is equal to a given number or another. For example I am doing this right now.
我必须检查一个变量是否等于给定的数字或另一个。例如，我现在正在这样做。
if (num == 1 || num == 3 || num == 4 || etc.) {
// Do something
} else if (num == 2 || num == 7 || num == 11 || etc.) {
// Do something
}
I thought there should be an easier way. for example an array of all numbers per if statement.
我认为应该有一种更简单的方法。例如，每个 if 语句的所有数字的数组。
var array1 = [1,3,4,5,6,8,9,10 etc.]
var array2 = [2,7,11,12,13,14 etc.]
And then see if the number is equal to anything inside one of these arrays. But I don't know how to do it..
然后查看该数字是否等于这些数组之一中的任何内容。但我不知道该怎么做..
回答by David
The indexOf() method searches the array for the specified item, and returns its position.
indexOf() 方法在数组中搜索指定项，并返回其位置。
var array1 = [1,3,4,5,6,8,9,10];
var a = array1.indexOf(46); //a = -1; if not found
If you need to support environments that don't have .indexOf(), you could implement the MDN fix.
如果您需要支持没有 .indexOf() 的环境，您可以实施MDN 修复。
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
"use strict";
if (this === void 0 || this === null) throw new TypeError();
var t = Object(this);
var len = t.length >>> 0;
if (len === 0) return -1;
var n = 0;
if (arguments.length > 0) {
n = Number(arguments[1]);
if (n !== n) // shortcut for verifying if it's NaN
n = 0;
else if (n !== 0 && n !== (1 / 0) && n !== -(1 / 0)) n = (n > 0 || -1) * Math.floor(Math.abs(n));
}
if (n >= len) return -1;
var k = n >= 0 ? n : Math.max(len - Math.abs(n), 0);
for (; k < len; k++) {
if (k in t && t[k] === searchElement) return k;
}
return -1;
};
}
回答by jdepypere
Since you're asking for jQuery, there is .inArray(). This returns a -1if it isn't found, else the index of the matching element.
由于您要求使用 jQuery，因此有.inArray()。-1如果未找到，则返回 a ，否则返回匹配元素的索引。
回答by Jivings
You don't need to use jQuery. This is a built in function called indexOf:
您不需要使用 jQuery。这是一个内置函数，称为indexOf：
if ( arr.indexOf(item) !== -1 ) {
// item is in array
}
回答by Armen
why dont you do a simple for loop?
你为什么不做一个简单的 for 循环？
for(var i = 0; i < array1.length; i++)
{
if(array[i] == num)
{
// do something
break;
}
}
回答by simongus
You might use inArrayfunction (http://api.jquery.com/jQuery.inArray/)
您可能会使用inArray函数（http://api.jquery.com/jQuery.inArray/）
<script>var arr = [ 4, "Pete", 8, "John" ];
var $spans = $("span");
$spans.eq(0).text(jQuery.inArray("John", arr));
$spans.eq(1).text(jQuery.inArray(4, arr));
$spans.eq(2).text(jQuery.inArray("Karl", arr));
$spans.eq(3).text(jQuery.inArray("Pete", arr, 2));
</script>
Output:
输出：
"John" found at 3 4 found at 0 "Karl" not found, so -1 "Pete" is in the array, but not at or after index 2, so -1
"John" found at 3 4 found at 0 "Karl" not found, 所以 -1 "Pete" 在数组中，但不在索引 2 处或之后，所以 -1
回答by Mihail
You can do it without jQuery:
你可以在没有 jQuery 的情况下做到：
if(array1.indexOf(num1) >= 0)//if -1, then not found
