{"slug": "javascript-string-methods", "title": "JavaScript String Methods", "summary": "A developer explains JavaScript string methods, covering properties like length and methods such as charAt, charCodeAt, codePointAt, concat, at, slice, substring, substr, toUpperCase, toLowerCase, isWellFormed, toWellFormed, trim, trimStart, trimEnd, padStart, padEnd, repeat, replace, replaceAll, and split.", "body_md": "A **String** in JavaScript is a sequence of characters used to store text.\n\n``` js\nlet course = \"JavaScript\";\n```\n\nReturns the total number of characters in a string.\n\n```\nstring.length\njs\nlet company = \"OpenAI\";\n\nconsole.log(company.length);\n6\n```\n\nChecking password length before registration.\n\nReturns the character at a specified index.\n\n```\nstring.charAt(index)\njs\nlet city = \"Madurai\";\n\nconsole.log(city.charAt(3));\nu\nM a d u r a i\n0 1 2 3 4 5 6\n```\n\nIndex 3 contains \"u\".\n\nReturns the Unicode value (UTF-16 code) of a character.\n\n``` js\nlet letter = \"A\";\n\nconsole.log(letter.charCodeAt(0));\n65\nconsole.log(\"a\".charCodeAt(0));\n```\n\nOutput:\n\n```\n97\n```\n\nReturns the Unicode code point of a character.\n\nUseful for emojis and special symbols.\n\n``` js\nlet emoji = \"😊\";\n\nconsole.log(emoji.codePointAt(0));\n128522\nconsole.log(\"😊\".charCodeAt(0));\nconsole.log(\"😊\".codePointAt(0));\n```\n\n`codePointAt()`\n\ngives the actual Unicode value.\n\nCombines two or more strings.\n\n``` js\nlet firstName = \"Annapoorani\";\nlet lastName = \" Kadhiravan\";\n\nlet fullName = firstName.concat(lastName);\n\nconsole.log(fullName);\nAnnapoorani Kadhiravan\nconsole.log(firstName + lastName);\n```\n\nReturns character at a specific position.\n\nSupports negative indexing.\n\n``` js\nlet language = \"JavaScript\";\n\nconsole.log(language.at(0));\nconsole.log(language.at(-1));\nJ\nt\n```\n\nAccess characters using bracket notation.\n\n``` js\nlet laptop = \"Dell\";\n\nconsole.log(laptop[0]);\nconsole.log(laptop[2]);\nD\nl\nconsole.log(laptop.charAt(0));\nconsole.log(laptop[0]);\n```\n\nBoth return same result.\n\nExtracts part of a string.\n\n```\nstring.slice(start,end)\njs\nlet course = \"JavaScript\";\n\nconsole.log(course.slice(0,4));\nJava\nconsole.log(course.slice(-6));\nScript\n```\n\nExtracts characters between indexes.\n\n``` js\nlet company = \"Microsoft\";\n\nconsole.log(company.substring(0,5));\nMicro\njs\nlet str = \"JavaScript\";\n\nconsole.log(str.slice(-6));\nconsole.log(str.substring(-6));\n```\n\nOutput:\n\n```\nScript\nJavaScript\n```\n\n`substring()`\n\ndoesn't support negative indexes.\n\n⚠️ Deprecated (Avoid in new projects)\n\nExtracts characters based on start position and length.\n\n``` js\nlet city = \"Chennai\";\n\nconsole.log(city.substr(2,4));\nenna\nStart at index 2\nTake 4 characters\n```\n\nConverts string to uppercase.\n\n``` js\nlet name = \"annapoorani\";\n\nconsole.log(name.toUpperCase());\nANNAPOORANI\n```\n\nConverts string to lowercase.\n\n``` js\nlet company = \"OPENAI\";\n\nconsole.log(company.toLowerCase());\nopenai\n```\n\nChecks whether a string contains valid Unicode characters.\n\n``` js\nlet text = \"Hello\";\n\nconsole.log(text.isWellFormed());\ntrue\n```\n\nUnicode validation before processing text.\n\nConverts malformed Unicode into valid Unicode.\n\n``` js\nlet text = \"\\uD800\";\n\nconsole.log(text.toWellFormed());\n�\n```\n\nCleaning corrupted text data.\n\nRemoves spaces from beginning and end.\n\n``` js\nlet email = \"  user@gmail.com  \";\n\nconsole.log(email.trim());\nuser@gmail.com\n```\n\nRemoves spaces only from beginning.\n\n``` js\nlet text = \"   Hello\";\n\nconsole.log(text.trimStart());\nHello\n```\n\nRemoves spaces only from end.\n\n``` js\nlet text = \"Hello   \";\n\nconsole.log(text.trimEnd());\nHello\n```\n\nAdds characters at the beginning until desired length.\n\n``` js\nlet orderId = \"123\";\n\nconsole.log(orderId.padStart(6,\"0\"));\n000123\n```\n\nGenerating invoice numbers.\n\nAdds characters at the end.\n\n``` js\nlet code = \"JS\";\n\nconsole.log(code.padEnd(5,\"*\"));\nJS***\n```\n\nRepeats a string multiple times.\n\n``` js\nlet star = \"*\";\n\nconsole.log(star.repeat(5));\n*****\n```\n\nPrinting separators.\n\nReplaces first matching occurrence.\n\n``` js\nlet sentence = \"I love Java. Java is powerful.\";\n\nconsole.log(sentence.replace(\"Java\",\"JavaScript\"));\nI love JavaScript. Java is powerful.\n```\n\nOnly first occurrence is replaced.\n\nReplaces all matching occurrences.\n\n``` js\nlet sentence = \"Java Java Java\";\n\nconsole.log(sentence.replaceAll(\"Java\",\"JS\"));\nJS JS JS\n```\n\nConverts string into array.\n\n``` js\nlet skills = \"HTML,CSS,JavaScript\";\n\nlet result = skills.split(\",\");\n\nconsole.log(result);\n[\"HTML\", \"CSS\", \"JavaScript\"]\njs\nlet sentence = \"Learning JavaScript Daily\";\n\nconsole.log(sentence.split(\" \"));\n[\"Learning\",\"JavaScript\",\"Daily\"]\n```\n\n| Method | Purpose |\n|---|---|\n| length | Count characters |\n| charAt() | Get character |\n| charCodeAt() | Unicode value |\n| codePointAt() | Unicode code point |\n| concat() | Join strings |\n| at() | Access character (supports negative index) |\n| [ ] | Access character |\n| slice() | Extract part of string |\n| substring() | Extract text (no negative index) |\n| substr() | Extract by length (deprecated) |\n| toUpperCase() | Convert to uppercase |\n| toLowerCase() | Convert to lowercase |\n| isWellFormed() | Check valid Unicode |\n| toWellFormed() | Fix invalid Unicode |\n| trim() | Remove spaces both sides |\n| trimStart() | Remove left spaces |\n| trimEnd() | Remove right spaces |\n| padStart() | Add characters at beginning |\n| padEnd() | Add characters at end |\n| repeat() | Repeat string |\n| replace() | Replace first match |\n| replaceAll() | Replace all matches |\n| split() | Convert string to array |\n\nReferences:\n\n[https://www.w3schools.com/js/js_string_methods.asp](https://www.w3schools.com/js/js_string_methods.asp)", "url": "https://wpnews.pro/news/javascript-string-methods", "canonical_source": "https://dev.to/annapoo/javascript-string-methods-3kll", "published_at": "2026-06-26 03:01:39+00:00", "updated_at": "2026-06-26 03:33:55.901562+00:00", "lang": "en", "topics": ["developer-tools"], "entities": ["JavaScript", "OpenAI", "Microsoft"], "alternates": {"html": "https://wpnews.pro/news/javascript-string-methods", "markdown": "https://wpnews.pro/news/javascript-string-methods.md", "text": "https://wpnews.pro/news/javascript-string-methods.txt", "jsonld": "https://wpnews.pro/news/javascript-string-methods.jsonld"}}