如何在textarea获得最大数量？ [英] How to get biggest number in textarea?

问题描述

我有这样的textarea：

I have a textarea like this:

<textarea>
this is a test [1] also this [2] is a test
and again [3] this is a test
</textarea>

现在我需要获得中最大的数字[] 。在这种情况下，我需要 3 。我怎么能这样做？

Now I need to get the biggest number which is in []. In this case I need to get 3. How can I do that?

推荐答案

你可以这样做：

var result = Math.max.apply(Math, textarea.value.match(/\d+/g).map(Number));

分手：

textarea.value.match(/\d+/g)

获取你是一个数字数组作为字符串。

Gets you an array of numbers as strings.

.map(Number)

将数组的每个条目从一个字符串映射到一个数字。

Maps each entry of the array from a string to a number.

Math.max.apply

致电 Math.max 使用此作为 Math 以及映射数组的参数。

Calls Math.max with this as Math and as parameters the mapped array.

编辑：我没有意识到你需要在括号之间做什么。你需要使用一个捕获组，现在它有点复杂。

Edit: I didn't realize what you needed had to be in between brackets. You'll need to use a capture group for that and it's a little bit more complicated now.

var reg = /\[(\d+)\]/g, numberStrings = [ ], match;
while((match = reg.exec(textarea.value)) !== null){
    numberStrings.push(match[1]);
}

var result = Math.max.apply(Math, numberStrings.map(Number));

使用数字获取字符串数组会有点棘手。

It's a little bit more tricky to get the array of strings with the numbers.

另一种选择，不使用捕获组：

Another alternative, without using a capture group:

var numbersInBrackets = textarea.value.match(/\[\d+\]/g);
var numbers = numbersInBrackets.map(function(x) {
    return Number(x.substring(1, x.length - 1));
});
var result = Math.max.apply(Math, numbers);

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