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"path": "/annapoo/javascript-string-methods-3kll",
"publishedAt": "2026-06-26T03:01:39.000Z",
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"textContent": "A **String** in JavaScript is a sequence of characters used to store text.\n\n\n\n let course = \"JavaScript\";\n\n\n# 1. String length\n\n### Purpose\n\nReturns the total number of characters in a string.\n\n### Syntax\n\n\n string.length\n\n\n### Example\n\n\n let company = \"OpenAI\";\n\n console.log(company.length);\n\n\n### Output\n\n\n 6\n\n\n### Real-Time Example\n\nChecking password length before registration.\n\n# 2. String charAt()\n\n### Purpose\n\nReturns the character at a specified index.\n\n### Syntax\n\n\n string.charAt(index)\n\n\n### Example\n\n\n let city = \"Madurai\";\n\n console.log(city.charAt(3));\n\n\n### Output\n\n\n u\n\n\n### Internal Logic\n\n\n M a d u r a i\n 0 1 2 3 4 5 6\n\n\nIndex 3 contains \"u\".\n\n# 3. String charCodeAt()\n\n### Purpose\n\nReturns the Unicode value (UTF-16 code) of a character.\n\n### Example\n\n\n let letter = \"A\";\n\n console.log(letter.charCodeAt(0));\n\n\n### Output\n\n\n 65\n\n\n### More Examples\n\n\n console.log(\"a\".charCodeAt(0));\n\n\nOutput:\n\n\n\n 97\n\n\n# 4. String codePointAt()\n\n### Purpose\n\nReturns the Unicode code point of a character.\n\nUseful for emojis and special symbols.\n\n### Example\n\n\n let emoji = \"š\";\n\n console.log(emoji.codePointAt(0));\n\n\n### Output\n\n\n 128522\n\n\n### Difference\n\n\n console.log(\"š\".charCodeAt(0));\n console.log(\"š\".codePointAt(0));\n\n\n`codePointAt()` gives the actual Unicode value.\n\n# 5. String concat()\n\n### Purpose\n\nCombines two or more strings.\n\n### Example\n\n\n let firstName = \"Annapoorani\";\n let lastName = \" Kadhiravan\";\n\n let fullName = firstName.concat(lastName);\n\n console.log(fullName);\n\n\n### Output\n\n\n Annapoorani Kadhiravan\n\n\n### Alternative\n\n\n console.log(firstName + lastName);\n\n\n# 6. String at()\n\n### Purpose\n\nReturns character at a specific position.\n\nSupports negative indexing.\n\n### Example\n\n\n let language = \"JavaScript\";\n\n console.log(language.at(0));\n console.log(language.at(-1));\n\n\n### Output\n\n\n J\n t\n\n\n# 7. String [ ]\n\n### Purpose\n\nAccess characters using bracket notation.\n\n### Example\n\n\n let laptop = \"Dell\";\n\n console.log(laptop[0]);\n console.log(laptop[2]);\n\n\n### Output\n\n\n D\n l\n\n\n### Difference\n\n\n console.log(laptop.charAt(0));\n console.log(laptop[0]);\n\n\nBoth return same result.\n\n# 8. String slice()\n\n### Purpose\n\nExtracts part of a string.\n\n### Syntax\n\n\n string.slice(start,end)\n\n\n### Example\n\n\n let course = \"JavaScript\";\n\n console.log(course.slice(0,4));\n\n\n### Output\n\n\n Java\n\n\n### Negative Index\n\n\n console.log(course.slice(-6));\n\n\n### Output\n\n\n Script\n\n\n# 9. String substring()\n\n### Purpose\n\nExtracts characters between indexes.\n\n### Example\n\n\n let company = \"Microsoft\";\n\n console.log(company.substring(0,5));\n\n\n### Output\n\n\n Micro\n\n\n### Difference from slice()\n\n\n let str = \"JavaScript\";\n\n console.log(str.slice(-6));\n console.log(str.substring(-6));\n\n\nOutput:\n\n\n\n Script\n JavaScript\n\n\n`substring()` doesn't support negative indexes.\n\n# 10. String substr()\n\nā ļø Deprecated (Avoid in new projects)\n\n### Purpose\n\nExtracts characters based on start position and length.\n\n### Example\n\n\n let city = \"Chennai\";\n\n console.log(city.substr(2,4));\n\n\n### Output\n\n\n enna\n\n\n### Explanation\n\n\n Start at index 2\n Take 4 characters\n\n\n# 11. String toUpperCase()\n\n### Purpose\n\nConverts string to uppercase.\n\n### Example\n\n\n let name = \"annapoorani\";\n\n console.log(name.toUpperCase());\n\n\n### Output\n\n\n ANNAPOORANI\n\n\n# 12. String toLowerCase()\n\n### Purpose\n\nConverts string to lowercase.\n\n### Example\n\n\n let company = \"OPENAI\";\n\n console.log(company.toLowerCase());\n\n\n### Output\n\n\n openai\n\n\n# 13. String isWellFormed()\n\n### Purpose\n\nChecks whether a string contains valid Unicode characters.\n\n### Example\n\n\n let text = \"Hello\";\n\n console.log(text.isWellFormed());\n\n\n### Output\n\n\n true\n\n\n### Use Case\n\nUnicode validation before processing text.\n\n# 14. String toWellFormed()\n\n### Purpose\n\nConverts malformed Unicode into valid Unicode.\n\n### Example\n\n\n let text = \"\\uD800\";\n\n console.log(text.toWellFormed());\n\n\n### Output\n\n\n ļæ½\n\n\n### Use Case\n\nCleaning corrupted text data.\n\n# 15. String trim()\n\n### Purpose\n\nRemoves spaces from beginning and end.\n\n### Example\n\n\n let email = \" user@gmail.com \";\n\n console.log(email.trim());\n\n\n### Output\n\n\n user@gmail.com\n\n\n# 16. String trimStart()\n\n### Purpose\n\nRemoves spaces only from beginning.\n\n### Example\n\n\n let text = \" Hello\";\n\n console.log(text.trimStart());\n\n\n### Output\n\n\n Hello\n\n\n# 17. String trimEnd()\n\n### Purpose\n\nRemoves spaces only from end.\n\n### Example\n\n\n let text = \"Hello \";\n\n console.log(text.trimEnd());\n\n\n### Output\n\n\n Hello\n\n\n# 18. String padStart()\n\n### Purpose\n\nAdds characters at the beginning until desired length.\n\n### Example\n\n\n let orderId = \"123\";\n\n console.log(orderId.padStart(6,\"0\"));\n\n\n### Output\n\n\n 000123\n\n\n### Real-Time Example\n\nGenerating invoice numbers.\n\n# 19. String padEnd()\n\n### Purpose\n\nAdds characters at the end.\n\n### Example\n\n\n let code = \"JS\";\n\n console.log(code.padEnd(5,\"*\"));\n\n\n### Output\n\n\n JS***\n\n\n# 20. String repeat()\n\n### Purpose\n\nRepeats a string multiple times.\n\n### Example\n\n\n let star = \"*\";\n\n console.log(star.repeat(5));\n\n\n### Output\n\n\n *****\n\n\n### Real-Time Example\n\nPrinting separators.\n\n# 21. String replace()\n\n### Purpose\n\nReplaces first matching occurrence.\n\n### Example\n\n\n let sentence = \"I love Java. Java is powerful.\";\n\n console.log(sentence.replace(\"Java\",\"JavaScript\"));\n\n\n### Output\n\n\n I love JavaScript. Java is powerful.\n\n\n### Note\n\nOnly first occurrence is replaced.\n\n# 22. String replaceAll()\n\n### Purpose\n\nReplaces all matching occurrences.\n\n### Example\n\n\n let sentence = \"Java Java Java\";\n\n console.log(sentence.replaceAll(\"Java\",\"JS\"));\n\n\n### Output\n\n\n JS JS JS\n\n\n# 23. String split()\n\n### Purpose\n\nConverts string into array.\n\n### Example\n\n\n let skills = \"HTML,CSS,JavaScript\";\n\n let result = skills.split(\",\");\n\n console.log(result);\n\n\n### Output\n\n\n [\"HTML\", \"CSS\", \"JavaScript\"]\n\n\n### Split by Space\n\n\n let sentence = \"Learning JavaScript Daily\";\n\n console.log(sentence.split(\" \"));\n\n\n### Output\n\n\n [\"Learning\",\"JavaScript\",\"Daily\"]\n\n\n# Quick Comparison Table\n\nMethod | Purpose\n---|---\nlength | Count characters\ncharAt() | Get character\ncharCodeAt() | Unicode value\ncodePointAt() | Unicode code point\nconcat() | Join strings\nat() | Access character (supports negative index)\n[ ] | Access character\nslice() | Extract part of string\nsubstring() | Extract text (no negative index)\nsubstr() | Extract by length (deprecated)\ntoUpperCase() | Convert to uppercase\ntoLowerCase() | Convert to lowercase\nisWellFormed() | Check valid Unicode\ntoWellFormed() | Fix invalid Unicode\ntrim() | Remove spaces both sides\ntrimStart() | Remove left spaces\ntrimEnd() | Remove right spaces\npadStart() | Add characters at beginning\npadEnd() | Add characters at end\nrepeat() | Repeat string\nreplace() | Replace first match\nreplaceAll() | Replace all matches\nsplit() | Convert string to array\n\nReferences:\nhttps://www.w3schools.com/js/js_string_methods.asp",
"title": "JavaScript String Methods"
}