How do I find the last element in an array with JavaScript? lastIndexOf (character, indexpos): This function gives the last index position of a character but start finding an element from the given index position in the inverse order. carbonScript.src = "//cdn.carbonads.com/carbon.js?serve=CE7IC2QE&placement=wwwjavascripttutorialnet"; Syntax: str.lastIndexOf (searchValue , index) Parameters: searchvalue: The searchvalue is the string that is to be searched in the base string. The lastIndexOf() method is case sensitive. slice () Extracts a part of a string and returns a new string. (Ep. Sorry in my first version I didn't take into account that the OP would like to get the index. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Are you sure the code works ? lastindexof method javascript lastindexof () javascript Comment 0 xxxxxxxxxx 'canal'.lastIndexOf('a'); // retorna 3 'canal'.lastIndexOf('a', 2); // retorna 1 'canal'.lastIndexOf('a', 0); // retorna -1 'canal'.lastIndexOf('x'); // retorna -1 'canal'.lastIndexOf('c', -5); // retorna 0 'canal'.lastIndexOf('c', 0); // retorna 0 The code may not follow naming conventions. This is different from the indexOf method. }. First, this is not an array of objects but an array of arrays. You can work around this by inserting the following code at the beginning of your scripts, allowing use of lastIndexOf in implementations which do not natively support it. As the indexing of a string starts from 0, str.lastIndexOf(substr) returns the value 7. The index of the last (highest-index) element in the array that passes the test. By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. A function to execute for each element in the array. indexOf () array method searches the element from start to end index while in case of lastIndexOf () array method searches from end to the starting index. This article is being improved by another user right now. If JS takes ee as one unit and returns its' index, why can't it return the lastIndexOf that unit? Content available under a Creative Commons license. This is more expensive. Temporary policy: Generative AI (e.g., ChatGPT) is banned. Syntax: string.lastIndexOf (searchValue [, fromIndex]) Parameter: This method accepts two parameter as mentioned above and described below: Note that we have to handle the case idx == 0 separately here because the element will always be found regardless of the fromIndex parameter if it is the first element of the array. In this example, we will provide the index value from where the search starts. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Again, note that this implementation aims for absolute compatibility with lastIndexOf in Firefox and the SpiderMonkey JavaScript engine, including in several . The returned index is the smallest value k for which: So if you want to find the ending index of any string you are looking for there is an easy way: Thanks for contributing an answer to Stack Overflow! The lastIndexOf () method returns the index of the last occurrence of the specified string value within the searched string. It's more functional but slicing and reversing the array will be significantly slower than iterating backwards. What is the state of the art of splitting a binary file by size? thanks. What's it called when multiple concepts are combined into a single problem? How do you find the index of the second e in sweet since both home.indexOf("ee") and home.lastIndexOf("ee") both return 7. From the JS perspective, filter is just 1 loop, but indexOf and lastIndexOf are supposed to be O(n) each internally. Here, we will print the position of a single character. Doping threaded gas pipes -- which threads are the "last" threads? All rights reserved. index always starts from the left. If the element is not found (-1), finalIndex will be the size of the array, not -1. $(location).attr('href').substring($(location).attr('href').lastIndexOf('/')+1); But what if I want to get the word projects? Search happens backwards by default starting at the last index of the. Connect and share knowledge within a single location that is structured and easy to search. Pros and cons of "anything-can-happen" UB versus allowing particular deviations from sequential progran execution, Labeling layer with two attributes in QGIS. If the fromIndex is less than zero, the search behavior is the same as if the fromIndex were zero. acknowledge that you have read and understood our. Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. lastIndexOf() Return Value. I dont do much JS but I would split string at '/' and grab the before last entry in the array. var carbonScript = document.createElement("script"); By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. lastIndexOf was added to the ECMA-262 standard in the 5th edition; as such it may not be present in other implementations of the standard. The following is a simple example, not tested, just for the idea. You can search for undefined in a sparse array and get the index of an empty slot. You can work around this by inserting the following code at the beginning of your scripts, allowing use of lastIndexOf in implementations which do not natively support it. lastIndexOf compares searchElement to elements of the Array using strict equality (the same method used by the ===, or triple-equals, operator). Specially for the while conditions that seems wrong. The lastIndexOf() method returns -1 if the value is not found. It starts searching the element from the provided index value and then returns the index position of first character of string. Enjoy our free tutorials like millions of other internet users since 1999, Explore our selection of references covering all popular coding languages, Create your own website with W3Schools Spaces - no setup required, Test your skills with different exercises, Test yourself with multiple choice questions, Create a free W3Schools Account to Improve Your Learning Experience, Track your learning progress at W3Schools and collect rewards, Become a PRO user and unlock powerful features (ad-free, hosting, videos,..), Not sure where you want to start? This page was last modified on Jul 14, 2023 by MDN contributors. It returns the length of the array instead of "-1". Asking for help, clarification, or responding to other answers. 589). The lastIndexOf () method returns the index from the beginning (position 0). : though this is not the most efficient solution, as we have to always traverse all array, whereas if we ran from end, we could end search the moment we found first match (@nico-timmerman's answer). Example 4: In this example, the method lastIndexOf() finds the last index of the string train in the string str. String.lastIndexOf ( ) searches the string from end to beginning to see if it contains an occurrence of substring. The following syntax demonstrates the String.lastIndexOf () method: 1 string.lastIndexOf (substring, [, startIndex]); If the substring does not found in string, It returns -1. Connect and share knowledge within a single location that is structured and easy to search. The lastIndexOf method returns -1 if the substring is not contained in the string.. Our if statement checks if the lastIndexOf method didn't return -1.. For example, I have a string like so: http://www.example.com/website/projects/2 I currently get the number 2 by using $ (location).attr ('href').substring ($ (location).attr ('href').lastIndexOf ('/')+1); But what if I want to get the word projects? Content available under a Creative Commons license. The lastIndexOf () method searches for the substring backward from the fromIndex. To find the second e when it may or may not form part of the string ee, use indexOf to find the first e, and then use it again passing the index of the character after first e as the second argument. O mtodo lastIndexOf () sensvel a letras maisculas e minsculas. If you intend to use this in real-world applications, you may be able to calculate from with less complicated code if you ignore those cases. If no elements satisfy the testing function, -1 is returned. Is this color scheme another standard for RJ45 cable? How to get the last array that includes a certain element? The cleanest way i found was using a single reduce. console.log(result); Output. Any issues to be expected to with Port of Entry Process? @EvanTrimboli it's impossible to find element in array without loop, even. This answer looks wrong to me. It calls a provided callbackFn function once for each element in an array in descending-index order, until callbackFn returns a truthy value. Since "Python" is not found in the "I love JavaScript" string, the method returns -1. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The method returns the index of the last occurrence of the specified substring at a position less than or equal to position, which defaults to +Infinity. The W3Schools online code editor allows you to edit code and view the result in your browser Enable JavaScript to view data. The lastIndexOf () method searches the string from the end to the beginning. See also the findLast() method, which returns the value of last element that satisfies the testing function (rather than its index). BCD tables only load in the browser with JavaScript enabled. Therefore: Warning: Concurrent modifications of the kind described above frequently lead to hard-to-understand code and are generally to be avoided (except in special cases). Since the string is not present in any index in str, therefore this method returns -1 as the answer. All browser compatibility updates at a glance, Frequently asked questions about MDN Plus. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. It starts searching the element from the provided index value in the inverse order and then returns the index position of specified char value. The String.prototype.lastIndexOf() returns the last occurrence of a substring (substr) in a string (str). lastIndexOf returns the index of the first character in the substring where the substring appears last in the superstring. If the fromIndex is greater or equal to str.length, the lastIndexOf () will search for the substr in the whole string. Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. Syntax: public int lastIndexOf (String str . How to remove empty trailing values and Carriage Return in JS Array? By using our site, you The search starts at a specified character position and proceeds backward toward the beginning of the string for the specified number of character positions. It's a proper solution. Bass line and chord mismatch - Afternoon in Paris. then get the last index of the array by getting the length of the array and minus '1' since array index always starts at '0'. Content available under a Creative Commons license. Description The lastIndexOf () method returns the index (position) of the last occurrence of a specified value in a string. To find the second e when it forms part of the string ee, use indexOf and then add 1 (you know the second character of ee is 1 character past the first character of the substring, so you know to add that much, if you want the last character of the substring, then you can calculate it using the .length of the substring). However, for elegance, here's code and the concept is simple: If a value appears only once in the array, then both indexOf and lastIndexOf should return the same index for a given value.