Determine if the given text includes a specific sequence of characters, without the need for them to be directly

Question

Determine if the given text includes a specific sequence of characters, without the need for them to be directly

I am developing a custom function that determines whether a specific sequence is present within a given text. Unlike traditional methods that check for substring inclusion, this function does not require the characters to be adjacent. For instance, in the string "Lord Of The Rings," the substrings "LOTR" or "other" should return true as they can be found within the string.

function checkSequence(text, sequence) {
    if (text.indexOf(sequence) !== -1){
        return true;
    }
    return false;
}

console.log(checkSequence("lord of the rings", "")); // True
console.log(checkSequence("lord of the rings", "lord")); // True
console.log(checkSequence("lord of the rings", "lens")); // True
console.log(checkSequence("lord of the rings", "other")); // True
console.log(checkSequence("lord of the rings", "l o t r")); // True
console.log(checkSequence("lord of the rings", "Lord")); // False
console.log(checkSequence("lord of the rings", "orks")); // False
console.log(checkSequence("lord of the rings", "z")); // False

However, the typical approach using indexOf() method might give incorrect results when checking for "LOTR" or "something." The code snippet provided showcases some examples I am currently testing with.

Thank you!

javascript string contains

Answer 1

Answer №1

Uninteresting (Yet Efficient) For-Loop Approach:

Revamped to end the loop immediately once the outcome is determined; like when there are more characters left in the sequence than in the text.

function contains(text, sequence) {
  for (var i = 0, j = 0; i < text.length && j < sequence.length; i++) {
    if (text.length - i < sequence.length - j) return false
    if (text[i] === sequence[j]) j++
  }
  return j === sequence.length
}


console.log(contains("lord of the rings", "")); // True
console.log(contains("lord of the rings", "lord")); // True
console.log(contains("lord of the rings", "lens")); // True
console.log(contains("lord of the rings", "other")); // True
console.log(contains("lord of the rings", "l o t r")); // True
console.log(contains("lord of the rings", "Lord")); // False
console.log(contains("lord of the rings", "orks")); // False
console.log(contains("lord of the rings", "z")); // False

Answer 2

Uninteresting (Yet Efficient) For-Loop Approach:

Revamped to end the loop immediately once the outcome is determined; like when there are more characters left in the sequence than in the text.

function contains(text, sequence) {
  for (var i = 0, j = 0; i < text.length && j < sequence.length; i++) {
    if (text.length - i < sequence.length - j) return false
    if (text[i] === sequence[j]) j++
  }
  return j === sequence.length
}


console.log(contains("lord of the rings", "")); // True
console.log(contains("lord of the rings", "lord")); // True
console.log(contains("lord of the rings", "lens")); // True
console.log(contains("lord of the rings", "other")); // True
console.log(contains("lord of the rings", "l o t r")); // True
console.log(contains("lord of the rings", "Lord")); // False
console.log(contains("lord of the rings", "orks")); // False
console.log(contains("lord of the rings", "z")); // False

Answer 3

Answer №2

To check if a text matches a specific sequence, you can convert the sequence into a regex pattern. Here's an example:

function checkMatch(text, sequence) {
  if(!sequence.length) return true;                       // returns true if sequence is empty
  
  var regex = new RegExp(sequence.split('').join('.*'));  // create the regex pattern

  return regex.test(text);                                // check if the text matches the regex pattern
}

console.log(checkMatch("lord of the rings", ""));
console.log(checkMatch("lord of the rings", "lord"));
console.log(checkMatch("lord of the rings", "lens"));
console.log(checkMatch("lord of the rings", "other"));
console.log(checkMatch("lord of the rings", "l o t r"));
console.log(checkMatch("lord of the rings", "Lord"));
console.log(checkMatch("lord of the rings", "orks"));
console.log(checkMatch("lord of the rings", "z"));

If the sequence is, for instance, 'txt', the generated regex would look like /t.*x.*t/. This regex will match the characters t, x, and t in that specific order with any number of characters (including none) in between.

Answer 4

To check if a text matches a specific sequence, you can convert the sequence into a regex pattern. Here's an example:

function checkMatch(text, sequence) {
  if(!sequence.length) return true;                       // returns true if sequence is empty
  
  var regex = new RegExp(sequence.split('').join('.*'));  // create the regex pattern

  return regex.test(text);                                // check if the text matches the regex pattern
}

console.log(checkMatch("lord of the rings", ""));
console.log(checkMatch("lord of the rings", "lord"));
console.log(checkMatch("lord of the rings", "lens"));
console.log(checkMatch("lord of the rings", "other"));
console.log(checkMatch("lord of the rings", "l o t r"));
console.log(checkMatch("lord of the rings", "Lord"));
console.log(checkMatch("lord of the rings", "orks"));
console.log(checkMatch("lord of the rings", "z"));

If the sequence is, for instance, 'txt', the generated regex would look like /t.*x.*t/. This regex will match the characters t, x, and t in that specific order with any number of characters (including none) in between.

Answer 5

Answer №3

To transform the ordered series, you can create a case-insensitive regex pattern like this:

/L.*O.*T.*R/i

...where .* represents zero or more occurrences of any character:

function checkForSequence(text, orderedSeries) {
  return (new RegExp(
            orderedSeries.split("")
                    .map( (character) => character.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') )
                    .join(".*"),
            "i")
         ).test(text)
}

console.log(checkForSequence("lord of the rings", "")); // True
console.log(checkForSequence("lord of the rings", "lord")); // True
console.log(checkForSequence("lord of the rings", "lens")); // True
console.log(checkForSequence("lord of the rings", "other")); // True
console.log(checkForSequence("lord of the rings", "l o t r")); // True
console.log(checkForSequence("lord of the rings", "Lord")); // True
console.log(checkForSequence("lord of the rings", "orks")); // False
console.log(checkForSequence("lord of the rings", "z")); // False
console.log(checkForSequence("Hi. How are you?", "i.?")); // True

The complicated

.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')

section is used to escape special characters in the input that may have significance in regular expressions.

Answer 6

To transform the ordered series, you can create a case-insensitive regex pattern like this:

/L.*O.*T.*R/i

...where .* represents zero or more occurrences of any character:

function checkForSequence(text, orderedSeries) {
  return (new RegExp(
            orderedSeries.split("")
                    .map( (character) => character.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') )
                    .join(".*"),
            "i")
         ).test(text)
}

console.log(checkForSequence("lord of the rings", "")); // True
console.log(checkForSequence("lord of the rings", "lord")); // True
console.log(checkForSequence("lord of the rings", "lens")); // True
console.log(checkForSequence("lord of the rings", "other")); // True
console.log(checkForSequence("lord of the rings", "l o t r")); // True
console.log(checkForSequence("lord of the rings", "Lord")); // True
console.log(checkForSequence("lord of the rings", "orks")); // False
console.log(checkForSequence("lord of the rings", "z")); // False
console.log(checkForSequence("Hi. How are you?", "i.?")); // True

The complicated

.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')

section is used to escape special characters in the input that may have significance in regular expressions.

Answer 7

Answer №4

If the order of the sequence is not important, utilizing a Set can be beneficial. The time complexity for this approach is O(n+m), which corresponds to the combined lengths of the text and the sequence.

To implement this method, store the characters in the Set and then utilize set.has(value) for verification.

function validatePresence(text, sequence) {
  var characterSet = new Set();
  for (var i = 0; i < text.length; i++) {
      characterSet.add(text[i]);
  }
  for (var i = 0; i < sequence.length; i++) {
     if(!characterSet.has(sequence[i])) return false;
  }
  return true;
}

Answer 8

If the order of the sequence is not important, utilizing a Set can be beneficial. The time complexity for this approach is O(n+m), which corresponds to the combined lengths of the text and the sequence.

To implement this method, store the characters in the Set and then utilize set.has(value) for verification.

function validatePresence(text, sequence) {
  var characterSet = new Set();
  for (var i = 0; i < text.length; i++) {
      characterSet.add(text[i]);
  }
  for (var i = 0; i < sequence.length; i++) {
     if(!characterSet.has(sequence[i])) return false;
  }
  return true;
}

Determine if the given text includes a specific sequence of characters, without the need for them to be directly

Answer №1

Uninteresting (Yet Efficient) For-Loop Approach:

Answer №2

Answer №3

Answer №4

Similar questions

Using SCSS to apply a class in Next.js

Creating directional light shadows in Three.JS: A Step-by-Step Guide

Creating a filter using radio input in HTML and CSS is a simple and

The MVC Controller is unable to retrieve decimal values from an Ajax POST request

Invoke the parent function when extending javascript prototype

Timeout error for WebSocket connection on JavaScript client

Vue Router configuration functions properly when accessed through URL directly

JavaScript For/in loop malfunctioning - Issue with undefined object property bug

Pressing the shortcut key will activate the function specified in ng-click,

Holding off on triggering a jQuery Ajax request until a function returns a value

Passing model data from view to controller via ajax request

Guide on how to reload the page with its initial URL after the URL has been modified using history.pushState()

Enhancing Google charts with vertical line effects on hover

Activate animation upon scrolling to specific element using Material-UI

Invalidating the express response object due to a TypeError issue

Guide on how to start the Bootstrap 4.6 collapse feature using JavaScript

Angular 5 offers the ability to incorporate dynamic checkbox input into your application

Array of JSON data passed in the request body

PHP is capable of showing echo statements from the function, however it does not directly showcase database information

The body request has been divided into various logs