If the length of the pointer, of the pattern, matches the length of the pattern, return the starting index of the pattern in the text.

If the current character in the text is equal to the current character in the pattern, increment the position of the current character in the pattern.

If the current character in the text is not equal to the current character in the pattern, reset the pointer, of the pattern, to the zeroth index.

Iterate through the string, character by character.If the pattern is an empty string, you can return true because.Let us decode through the flow, step by step: The KMP Algorithm takes a linear approach to check if the substring, is present in the string or not. This is much faster, and better than the naive ones. Knuth-Morris-Pratt Algorithm alias KMP-Algorithmįirst things first, the KMP-Algorithm takes a time complexity of O(m+n). If you are aiming for a solution that takes a lessor time complexity, you need to use a different algorithm. Whether you use includes, or indexOf - both the naive algorithms take a time complexity of O(m * n), where m is the length of the parent string and n is the length of the substring. IndexOf does a case-sensitive search on the string. var string = 'foo' var substring = 'oo' console.log(string.indexOf(substring) != -1) // true

It is often used in arrays, and the same can be applied with strings. The indexOf method would return -1 if the substring is not present in the string.

IndexOf can be used to decide if the string, contains a substring or not. This means, you must have a fallback mechanism in your code to handle these environments. Older browsers, and especially Internet Explorer does not support. Includes does a case-sensitive search on the string.Īs developers, you need to be watchful off when the includes is being used. If you are using the most recent version of JavaScript, for development, you have the liberty of using the includes function in the String Prototype.ĮCMAScript 6 introduced const string = 'foo' const substring = 'oo' console.log(string.includes(substring)) // true

Javascript string search