JavaScript：如何捕获字符串中的特定值？

Question

我有以下字符串，我需要从 Mem: 行中捕获第 31 位数字。空间是动态的，所以我无法捕捉到正确的数字。

细绳：

Swap:            1          0          1        

Mem:            31         27          3          0          1         18

我正在尝试下面的代码，但不能再进一步了。

let lines = output.split('\n');

for (var i = 0; i < lines.length; i++) {

  var newArray = lines[i];

  if (newArray.indexOf('Mem:') > -1) {

    let n = newArray.split(":");

  }

}

Answer 1

您可以使用正则表达式Mem:\s*(\d+)将第一个数字Mem:和未知数量的空格获取到捕获组。然后用于match获取位于 index 的捕获组1。const str = `Swap:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;Mem:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 31&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;27&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;18`const [, number] = str.match(/Mem:\s*(\d+)/)console.log(number)

Answer 2

提供 'Mem' 字符串（大概来自您的lines数组），就这么简单：const str = "Mem:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 31122&nbsp; &nbsp; &nbsp; &nbsp;27&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;18";const subStr = str.split(':')[1].trim();const num = subStr.substr(0,subStr.indexOf(' '));console.log(num);如果问题中没有确定其他约束，我会根据需要更改答案。

Answer 3

var lines = 'Swap:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; \nMem:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 31&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;27&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;18',&nbsp; &nbsp; firstNum = lines.split('\n').find(s => s.includes('Mem')).match(/\d+/);console.log(firstNum[0]);