Question

我已经能够找到有关如何删除字符串的最后一个单词的示例，但是在这种情况下，我试图删除字符串的最后3个单词。我尝试通过调整一些我遇到的答案来删除单个单词来尝试此操作，但是没有一个给我预期的结果。

示例字符串Highest ranked in the states

我希望我的返回值为Highest ranked

以下是我尝试过的代码片段：

let myString = "Highest ranked in the states";

myString = myString.substring(2, myString.lastIndexOf(" "));

console.log(myString)


let myString2 = "I want to remove the last word";
let mySplitResult2 = myString2.split(" ");
let lastWord =  mySplitResult2[mySplitResult2.length-3] 

console.log(lastWord)

通过将子字符串方法调整为(2, myString.lastIndexOf(" "));，最终删除了我句子的前两个字母，只删除了states一词，例如“来宾排名”。

将.split（）方法的长度调整为-3时，它只是返回单词in而不是in the states

Answer 1

这是一个很好的可读性的衬纸：

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您可以通过以下方式轻松地将其概括为const remove3words = words => words.split(" ").slice(0, -3).join(" "); console.log(remove3words("Highest ranked in the states")); console.log(remove3words("Exactly three words"));个单词：

Answer 2

有关使用拆分和拼接的说明，请参见注释

let myString = "Highest ranked in the states";
//split the str using blank space between each word and add to new variable
let str = myString.split(" ");
//get the length 
let num = str.length;
//splice the array removing the last three values with the number - 3
let newStr = str.splice(0, num - 3);

let displayText = '';
//back into string
newStr.forEach(function(value){
  displayText += value + ' ';
});
display.textContent = displayText;

<div id="display"></div>

Answer 3

let myString = "Highest ranked in the states";

myString = myString.split(' ')
myString = myString.splice(myString.length-5,2)
myString = myString.join(' ')

console.log(myString)

Answer 4

这是可以为您完成此功能的功能。（实际上，它可以从您指定的任何字符的倒数第二个字符中删除所有字符，而不仅仅是倒数第二个单词。）

在您的情况下：

char参数应获取值' ' （即单词之间的空格）
N应该获得值3 （以倒数第三位为目标）

我添加了一个 excludeChar参数，您可以将其设置为true ，以避免返回最终空格（或者您可以对结果使用.trim方法）。

const
  myString = "Highest ranked in the states",
  result = truncateAtNthToLastOccurencOfChar(myString, ' ', 3);
console.log(result);


function truncateAtNthToLastOccurencOfChar(str, char, N, excludeChar){

  // Makes counter,  converts str to arr & reverses it
  let i = -1, rev = Array.from(str).reverse();

  // Increments counter (and executes even when i=0)
  while(++i || true){

    // Returns original string if at the end `char` has occured fewer than `N` times
    if(i >= rev.length - 1){
      return str;
    }

    // If current character matches `char`, decrements `N`
    if(rev[i] == char && --N === 0){

      // If N=0, `i` is our target, all keeps characters (from reversed array)
      //   starting at `i` (or after `i` if excludeChar=true)
      return rev
        // The occurence of char can be excluded from result
        .slice(excludeChar ? (i + 1) : i)
        .reverse() // Restores original character order
        .join(''); // Converts back to string
    }
  }
}

Javascript-从字符串中删除最后3个单词

4 个答案: