使用 JavaScript 拆分大写字母的字符串

在 JavaScript 中拆分大写字母的字符串

Split a String on Capital Letters using JavaScript

使用正则表达式调用该split()方法以拆分大写字母的字符串，例如str.split(/(?=[A-Z])/);.

正则表达式使用肯定的先行断言来拆分每个大写字母上的字符串。

const str = 'BobbyHadzCom';

const result = str.split(/(?=[A-Z])/);

// 👇️ [ 'Bobby', 'Hadz', 'Com' ]
console.log(result);

我们传递给String.split方法的唯一参数

是一个正则表达式。

正斜杠标记/ /正则表达式的开始和结束。

处理尾随空格

如果您的字符串包含空格，则数组中的子字符串将包含尾随空格。

const str = 'Bobby Hadz Com';

const result = str.split(/(?=[A-Z])/);

// 👇️ [ 'Bobby ', 'Hadz ', 'Com' ]
console.log(result);

同样，如果字符串以空格开头，您将得到一个包含空格的数组元素。

const str = ' Bobby Hadz Com ';

const result = str.split(/(?=[A-Z])/);

// 👇️ [ ' ', 'Bobby ', 'Hadz ', 'Com ' ]
console.log(result);

我们可以使用
String.trim()
和
Array.map()
方法来处理这些边缘情况。

const str = ' Bobby Hadz Com ';

const result = str
  .trim()
  .split(/(?=[A-Z])/)
  .map(element => element.trim());

// 👇️ [ 'Bobby', 'Hadz', 'Com' ]
console.log(result);

我们使用该trim()方法从原始字符串中删除任何前导和尾随空格。

// 👇️ "abc"
console.log(' abc '.trim());

然后我们调用该split()方法在每个大写字母上拆分字符串。

最后，我们使用该Array.map()方法从数组中的字符串中删除任何前导或尾随空格。

On each iteration, we trim the string to remove the leading and trailing spaces
and return the result.

The Array.map method returns a new array that contains the values we returned
from the callback function.

If you have to do this often, define a reusable function.

function splitOnCapital(str) {
  return str
    .trim()
    .split(/(?=[A-Z])/)
    .map(element => element.trim());
}

const str = ' Bobby Hadz Com ';

const result = splitOnCapital(str);
console.log(result); // 👉️ [ 'Bobby', 'Hadz', 'Com' ]

The splitOnCapital function takes a string and splits it on each capital
letter.

Split a String on Capital Letters using String.match() #

Alternatively, you can use the String.match() method.

function splitOnCapital(str) {
  return str
    .trim()
    .match(/([A-Z]?[^A-Z]*)/g)
    .map(element => element.trim())
    .filter(element => element);
}

const str = ' Bobby Hadz Com ';

const result = splitOnCapital(str);
console.log(result); // 👉️ [ 'Bobby', 'Hadz', 'Com' ]

The
String.match
method matches a string against a regular expression.

The method returns an array containing the matches (if any) or null if no
matches are found.

The forward slashes / / mark the beginning and end of the regular expression.

The [A-Z] character class matches the capital letters from A to Z.

function splitOnCapital(str) {
  return str
    .trim()
    .match(/([A-Z]?[^A-Z]*)/g)
    .map(element => element.trim())
    .filter(element => element);
}

The question mark ? matches the preceding item (the capital letters) 0 or 1
times.

The caret ^ symbol means “NOT the following”.

So, the [^A-Z] character class matches any character that is not a capital
letter.

The asterisk * matches the preceding item (non-capital letters) zero or more
times.

The g flag is used because we want to match all occurrences of the regular
expression and not just the first occurrence.

If you ever need help reading a regular expression, check out this
regular expression cheatsheet
by MDN.

It contains a table with the name and the meaning of each special character with
examples.