From e288b073b96d87555328dffcedcaa8f55c6a2b6f Mon Sep 17 00:00:00 2001
From: Krzysztof kuhy Rudnicki <krzysztofrudnicki0@gmail.com>
Date: Sun, 4 Oct 2026 22:45:34 +0200
Subject: [PATCH] js_anki: prettier-format string.json

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 python_pkg/js_anki/string.json | 377 ++++++++++++++++++++++++++++++---
 1 file changed, 345 insertions(+), 32 deletions(-)

diff --git a/python_pkg/js_anki/string.json b/python_pkg/js_anki/string.json
index a635e55f..34e9657d 100644
--- a/python_pkg/js_anki/string.json
+++ b/python_pkg/js_anki/string.json
@@ -1,34 +1,347 @@
 [
- {"method":"charAt / s[i]","tier":"core","task":"Get the character at index i","call":"s[i]   // or s.charAt(i)","mutates":false,"returns":"1-char string; s[i] gives undefined out of range, charAt gives ''","example":"return ['abc'[1],'abc'.charAt(5),'abc'[5]];","expected":"[\"b\",\"\",null]","gotcha":"Strings are immutable: s[0] = 'x' silently does nothing."},
- {"method":"charCodeAt","tier":"core","task":"Get the char code of the character at index i","call":"s.charCodeAt(i)","mutates":false,"returns":"number (UTF-16 code unit)","example":"return ['a'.charCodeAt(0),'c'.charCodeAt(0)-'a'.charCodeAt(0)];","expected":"[97,2]","gotcha":"Alphabet index idiom: s.charCodeAt(i) - 97."},
- {"method":"String.fromCharCode","tier":"core","task":"Turn a char code into a character","call":"String.fromCharCode(code)","mutates":false,"returns":"string","example":"return String.fromCharCode(97+2);","expected":"\"c\"","gotcha":"Static method on String, not on a string value."},
- {"method":"split","tier":"core","task":"Split a string into an array by a separator","call":"s.split(sep)","mutates":false,"returns":"array of strings","signature":"s.split(separator, limit)  // split('') = chars","example":"return ['a,b'.split(','),'abc'.split('')];","expected":"[[\"a\",\"b\"],[\"a\",\"b\",\"c\"]]"},
- {"method":"[...s]","tier":"core","task":"Turn a string into an array of characters","call":"[...s]   // or Array.from(s)","mutates":false,"returns":"new array of characters","example":"return [...'abc'];","expected":"[\"a\",\"b\",\"c\"]","gotcha":"Unlike split(''), spread keeps emoji/surrogate pairs whole."},
- {"method":"reverse a string","tier":"core","task":"Reverse a string","call":"[...s].reverse().join('')","mutates":false,"returns":"new string","example":"return [...'abc'].reverse().join('');","expected":"\"cba\"","gotcha":"Strings have no reverse(); go via an array."},
- {"method":"slice","tier":"core","task":"Get s[i..j) as a substring","call":"s.slice(i, j)","mutates":false,"returns":"new string; end exclusive","signature":"s.slice(start, end)  // end exclusive, negatives count from the end","example":"return ['abcdef'.slice(1,3),'abcdef'.slice(-2)];","expected":"[\"bc\",\"ef\"]"},
- {"method":"substring","tier":"core","task":"Substring by two indices (and how it differs from slice)","call":"s.substring(i, j)","mutates":false,"returns":"new string; end exclusive","signature":"s.substring(start, end)  // swaps args if start > end, negatives → 0","example":"return ['abcdef'.substring(3,1),'abcdef'.slice(3,1),'abcdef'.substring(-2)];","expected":"[\"bc\",\"\",\"abcdef\"]","gotcha":"Prefer slice(): substring swaps arguments and treats negatives as 0."},
- {"method":"indexOf","tier":"core","task":"Find the index of a substring (-1 if absent)","call":"s.indexOf(sub)","mutates":false,"returns":"first index, or -1","signature":"s.indexOf(searchString, fromIndex)","example":"return ['hello'.indexOf('l'),'hello'.indexOf('z')];","expected":"[2,-1]"},
- {"method":"includes","tier":"core","task":"Check whether a string contains a substring","call":"s.includes(sub)","mutates":false,"returns":"boolean","example":"return 'hello'.includes('ell');","expected":"true","gotcha":"Case-sensitive; a RegExp argument throws."},
- {"method":"startsWith","tier":"core","task":"Check whether a string starts with a prefix","call":"s.startsWith(prefix)","mutates":false,"returns":"boolean","example":"return 'hello'.startsWith('he');","expected":"true"},
- {"method":"endsWith","tier":"core","task":"Check whether a string ends with a suffix","call":"s.endsWith(suffix)","mutates":false,"returns":"boolean","example":"return 'hello'.endsWith('lo');","expected":"true"},
- {"method":"toLowerCase","tier":"core","task":"Lowercase a string","call":"s.toLowerCase()","mutates":false,"returns":"new string","example":"return 'aBc'.toLowerCase();","expected":"\"abc\""},
- {"method":"toUpperCase","tier":"core","task":"Uppercase a string","call":"s.toUpperCase()","mutates":false,"returns":"new string","example":"return 'aBc'.toUpperCase();","expected":"\"ABC\""},
- {"method":"trim","tier":"core","task":"Strip whitespace from both ends","call":"s.trim()","mutates":false,"returns":"new string","example":"return '  a b '.trim();","expected":"\"a b\""},
- {"method":"repeat","tier":"core","task":"Repeat a string n times","call":"s.repeat(n)","mutates":false,"returns":"new string","example":"return 'ab'.repeat(3);","expected":"\"ababab\"","gotcha":"Negative n throws RangeError."},
- {"method":"padStart","tier":"core","task":"Left-pad a string to a length (e.g. zero-pad)","call":"s.padStart(len, '0')","mutates":false,"returns":"new string","signature":"s.padStart(targetLength, padString)","example":"return '5'.padStart(3,'0');","expected":"\"005\""},
- {"method":"padEnd","tier":"core","task":"Right-pad a string to a length","call":"s.padEnd(len, ' ')","mutates":false,"returns":"new string","signature":"s.padEnd(targetLength, padString)","example":"return 'ab'.padEnd(5,'.');","expected":"\"ab...\""},
- {"method":"replace","tier":"core","task":"Replace occurrences of a pattern (first only vs all)","call":"s.replace(pattern, replacement)","mutates":false,"returns":"new string","signature":"s.replace(patternOrString, replacementOrFn)","example":"return ['aaa'.replace('a','b'),'aaa'.replace(/a/g,'b')];","expected":"[\"baa\",\"bbb\"]","gotcha":"A string pattern replaces only the FIRST match. Use /x/g or replaceAll."},
- {"method":"replaceAll","tier":"core","task":"Replace ALL occurrences of a substring","call":"s.replaceAll(sub, replacement)","mutates":false,"returns":"new string","signature":"s.replaceAll(patternOrString, replacementOrFn)","example":"return 'aaa'.replaceAll('a','b');","expected":"\"bbb\"","gotcha":"A RegExp argument must have the g flag or it throws."},
- {"method":"at","tier":"core","task":"Get the LAST character (or nth from the end)","call":"s.at(-1)","mutates":false,"returns":"1-char string, or undefined","example":"return ['abc'.at(-1),'abc'.at(0)];","expected":"[\"c\",\"a\"]"},
- {"method":"match","tier":"core","task":"Find all regex matches in a string","call":"s.match(/\\d+/g)","mutates":false,"returns":"array of matches, or null if none","example":"return ['a1b22'.match(/\\d+/g),'abc'.match(/\\d+/g)];","expected":"[[\"1\",\"22\"],null]","gotcha":"Without the g flag you get a single match object, not all matches. null → use ?? []."},
- {"method":"matchAll","tier":"core","task":"Iterate all regex matches including capture groups","call":"[...s.matchAll(/(\\d)(\\w)/g)]","mutates":false,"returns":"iterator of match arrays","example":"return [...'1a2b'.matchAll(/(\\d)(\\w)/g)].map((m)=>m[1]+m[2]);","expected":"[\"1a\",\"2b\"]","gotcha":"The regex must have the g flag or it throws."},
- {"method":"trimStart","tier":"rare","task":"Strip whitespace from the START only","call":"s.trimStart()","mutates":false,"returns":"new string","example":"return '  a '.trimStart();","expected":"\"a \""},
- {"method":"trimEnd","tier":"rare","task":"Strip whitespace from the END only","call":"s.trimEnd()","mutates":false,"returns":"new string","example":"return '  a '.trimEnd();","expected":"\"  a\""},
- {"method":"lastIndexOf","tier":"rare","task":"Find the LAST index of a substring","call":"s.lastIndexOf(sub)","mutates":false,"returns":"last index, or -1","example":"return 'hello'.lastIndexOf('l');","expected":"3"},
- {"method":"substr","tier":"rare","task":"Substring by start index and LENGTH (deprecated)","call":"s.substr(start, length)","mutates":false,"returns":"new string","signature":"s.substr(start, length)  // deprecated; use slice","example":"return 'abcdef'.substr(1,3);","expected":"\"bcd\"","gotcha":"Second arg is a length, not an end index. Deprecated."},
- {"method":"concat","tier":"rare","task":"Concatenate strings with a method call","call":"s.concat(a, b)","mutates":false,"returns":"new string","example":"return 'a'.concat('b','c');","expected":"\"abc\"","gotcha":"Just use + or a template literal."},
- {"method":"search","tier":"rare","task":"Find the index of a regex match","call":"s.search(/c/)","mutates":false,"returns":"index, or -1","example":"return 'abc'.search(/c/);","expected":"2"},
- {"method":"localeCompare","tier":"rare","task":"Compare two strings for sorting","call":"a.localeCompare(b)","mutates":false,"returns":"negative / 0 / positive number","example":"return ['b','a','c'].sort((x,y)=>x.localeCompare(y));","expected":"[\"a\",\"b\",\"c\"]","gotcha":"Locale-aware and slower; for plain code-unit order use a < b ? -1 : 1."},
- {"method":"codePointAt","tier":"rare","task":"Get the full Unicode code point at index i","call":"s.codePointAt(i)","mutates":false,"returns":"number","example":"return '😀'.codePointAt(0);","expected":"128512","gotcha":"charCodeAt would return only half of the surrogate pair."},
- {"method":"normalize","tier":"rare","task":"Normalize Unicode (e.g. strip accents with NFD)","call":"s.normalize('NFD')","mutates":false,"returns":"new string","example":"return 'é'.normalize('NFD').length;","expected":"2"}
+  {
+    "method": "charAt / s[i]",
+    "tier": "core",
+    "task": "Get the character at index i",
+    "call": "s[i]   // or s.charAt(i)",
+    "mutates": false,
+    "returns": "1-char string; s[i] gives undefined out of range, charAt gives ''",
+    "example": "return ['abc'[1],'abc'.charAt(5),'abc'[5]];",
+    "expected": "[\"b\",\"\",null]",
+    "gotcha": "Strings are immutable: s[0] = 'x' silently does nothing."
+  },
+  {
+    "method": "charCodeAt",
+    "tier": "core",
+    "task": "Get the char code of the character at index i",
+    "call": "s.charCodeAt(i)",
+    "mutates": false,
+    "returns": "number (UTF-16 code unit)",
+    "example": "return ['a'.charCodeAt(0),'c'.charCodeAt(0)-'a'.charCodeAt(0)];",
+    "expected": "[97,2]",
+    "gotcha": "Alphabet index idiom: s.charCodeAt(i) - 97."
+  },
+  {
+    "method": "String.fromCharCode",
+    "tier": "core",
+    "task": "Turn a char code into a character",
+    "call": "String.fromCharCode(code)",
+    "mutates": false,
+    "returns": "string",
+    "example": "return String.fromCharCode(97+2);",
+    "expected": "\"c\"",
+    "gotcha": "Static method on String, not on a string value."
+  },
+  {
+    "method": "split",
+    "tier": "core",
+    "task": "Split a string into an array by a separator",
+    "call": "s.split(sep)",
+    "mutates": false,
+    "returns": "array of strings",
+    "signature": "s.split(separator, limit)  // split('') = chars",
+    "example": "return ['a,b'.split(','),'abc'.split('')];",
+    "expected": "[[\"a\",\"b\"],[\"a\",\"b\",\"c\"]]"
+  },
+  {
+    "method": "[...s]",
+    "tier": "core",
+    "task": "Turn a string into an array of characters",
+    "call": "[...s]   // or Array.from(s)",
+    "mutates": false,
+    "returns": "new array of characters",
+    "example": "return [...'abc'];",
+    "expected": "[\"a\",\"b\",\"c\"]",
+    "gotcha": "Unlike split(''), spread keeps emoji/surrogate pairs whole."
+  },
+  {
+    "method": "reverse a string",
+    "tier": "core",
+    "task": "Reverse a string",
+    "call": "[...s].reverse().join('')",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return [...'abc'].reverse().join('');",
+    "expected": "\"cba\"",
+    "gotcha": "Strings have no reverse(); go via an array."
+  },
+  {
+    "method": "slice",
+    "tier": "core",
+    "task": "Get s[i..j) as a substring",
+    "call": "s.slice(i, j)",
+    "mutates": false,
+    "returns": "new string; end exclusive",
+    "signature": "s.slice(start, end)  // end exclusive, negatives count from the end",
+    "example": "return ['abcdef'.slice(1,3),'abcdef'.slice(-2)];",
+    "expected": "[\"bc\",\"ef\"]"
+  },
+  {
+    "method": "substring",
+    "tier": "core",
+    "task": "Substring by two indices (and how it differs from slice)",
+    "call": "s.substring(i, j)",
+    "mutates": false,
+    "returns": "new string; end exclusive",
+    "signature": "s.substring(start, end)  // swaps args if start > end, negatives → 0",
+    "example": "return ['abcdef'.substring(3,1),'abcdef'.slice(3,1),'abcdef'.substring(-2)];",
+    "expected": "[\"bc\",\"\",\"abcdef\"]",
+    "gotcha": "Prefer slice(): substring swaps arguments and treats negatives as 0."
+  },
+  {
+    "method": "indexOf",
+    "tier": "core",
+    "task": "Find the index of a substring (-1 if absent)",
+    "call": "s.indexOf(sub)",
+    "mutates": false,
+    "returns": "first index, or -1",
+    "signature": "s.indexOf(searchString, fromIndex)",
+    "example": "return ['hello'.indexOf('l'),'hello'.indexOf('z')];",
+    "expected": "[2,-1]"
+  },
+  {
+    "method": "includes",
+    "tier": "core",
+    "task": "Check whether a string contains a substring",
+    "call": "s.includes(sub)",
+    "mutates": false,
+    "returns": "boolean",
+    "example": "return 'hello'.includes('ell');",
+    "expected": "true",
+    "gotcha": "Case-sensitive; a RegExp argument throws."
+  },
+  {
+    "method": "startsWith",
+    "tier": "core",
+    "task": "Check whether a string starts with a prefix",
+    "call": "s.startsWith(prefix)",
+    "mutates": false,
+    "returns": "boolean",
+    "example": "return 'hello'.startsWith('he');",
+    "expected": "true"
+  },
+  {
+    "method": "endsWith",
+    "tier": "core",
+    "task": "Check whether a string ends with a suffix",
+    "call": "s.endsWith(suffix)",
+    "mutates": false,
+    "returns": "boolean",
+    "example": "return 'hello'.endsWith('lo');",
+    "expected": "true"
+  },
+  {
+    "method": "toLowerCase",
+    "tier": "core",
+    "task": "Lowercase a string",
+    "call": "s.toLowerCase()",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return 'aBc'.toLowerCase();",
+    "expected": "\"abc\""
+  },
+  {
+    "method": "toUpperCase",
+    "tier": "core",
+    "task": "Uppercase a string",
+    "call": "s.toUpperCase()",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return 'aBc'.toUpperCase();",
+    "expected": "\"ABC\""
+  },
+  {
+    "method": "trim",
+    "tier": "core",
+    "task": "Strip whitespace from both ends",
+    "call": "s.trim()",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return '  a b '.trim();",
+    "expected": "\"a b\""
+  },
+  {
+    "method": "repeat",
+    "tier": "core",
+    "task": "Repeat a string n times",
+    "call": "s.repeat(n)",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return 'ab'.repeat(3);",
+    "expected": "\"ababab\"",
+    "gotcha": "Negative n throws RangeError."
+  },
+  {
+    "method": "padStart",
+    "tier": "core",
+    "task": "Left-pad a string to a length (e.g. zero-pad)",
+    "call": "s.padStart(len, '0')",
+    "mutates": false,
+    "returns": "new string",
+    "signature": "s.padStart(targetLength, padString)",
+    "example": "return '5'.padStart(3,'0');",
+    "expected": "\"005\""
+  },
+  {
+    "method": "padEnd",
+    "tier": "core",
+    "task": "Right-pad a string to a length",
+    "call": "s.padEnd(len, ' ')",
+    "mutates": false,
+    "returns": "new string",
+    "signature": "s.padEnd(targetLength, padString)",
+    "example": "return 'ab'.padEnd(5,'.');",
+    "expected": "\"ab...\""
+  },
+  {
+    "method": "replace",
+    "tier": "core",
+    "task": "Replace occurrences of a pattern (first only vs all)",
+    "call": "s.replace(pattern, replacement)",
+    "mutates": false,
+    "returns": "new string",
+    "signature": "s.replace(patternOrString, replacementOrFn)",
+    "example": "return ['aaa'.replace('a','b'),'aaa'.replace(/a/g,'b')];",
+    "expected": "[\"baa\",\"bbb\"]",
+    "gotcha": "A string pattern replaces only the FIRST match. Use /x/g or replaceAll."
+  },
+  {
+    "method": "replaceAll",
+    "tier": "core",
+    "task": "Replace ALL occurrences of a substring",
+    "call": "s.replaceAll(sub, replacement)",
+    "mutates": false,
+    "returns": "new string",
+    "signature": "s.replaceAll(patternOrString, replacementOrFn)",
+    "example": "return 'aaa'.replaceAll('a','b');",
+    "expected": "\"bbb\"",
+    "gotcha": "A RegExp argument must have the g flag or it throws."
+  },
+  {
+    "method": "at",
+    "tier": "core",
+    "task": "Get the LAST character (or nth from the end)",
+    "call": "s.at(-1)",
+    "mutates": false,
+    "returns": "1-char string, or undefined",
+    "example": "return ['abc'.at(-1),'abc'.at(0)];",
+    "expected": "[\"c\",\"a\"]"
+  },
+  {
+    "method": "match",
+    "tier": "core",
+    "task": "Find all regex matches in a string",
+    "call": "s.match(/\\d+/g)",
+    "mutates": false,
+    "returns": "array of matches, or null if none",
+    "example": "return ['a1b22'.match(/\\d+/g),'abc'.match(/\\d+/g)];",
+    "expected": "[[\"1\",\"22\"],null]",
+    "gotcha": "Without the g flag you get a single match object, not all matches. null → use ?? []."
+  },
+  {
+    "method": "matchAll",
+    "tier": "core",
+    "task": "Iterate all regex matches including capture groups",
+    "call": "[...s.matchAll(/(\\d)(\\w)/g)]",
+    "mutates": false,
+    "returns": "iterator of match arrays",
+    "example": "return [...'1a2b'.matchAll(/(\\d)(\\w)/g)].map((m)=>m[1]+m[2]);",
+    "expected": "[\"1a\",\"2b\"]",
+    "gotcha": "The regex must have the g flag or it throws."
+  },
+  {
+    "method": "trimStart",
+    "tier": "rare",
+    "task": "Strip whitespace from the START only",
+    "call": "s.trimStart()",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return '  a '.trimStart();",
+    "expected": "\"a \""
+  },
+  {
+    "method": "trimEnd",
+    "tier": "rare",
+    "task": "Strip whitespace from the END only",
+    "call": "s.trimEnd()",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return '  a '.trimEnd();",
+    "expected": "\"  a\""
+  },
+  {
+    "method": "lastIndexOf",
+    "tier": "rare",
+    "task": "Find the LAST index of a substring",
+    "call": "s.lastIndexOf(sub)",
+    "mutates": false,
+    "returns": "last index, or -1",
+    "example": "return 'hello'.lastIndexOf('l');",
+    "expected": "3"
+  },
+  {
+    "method": "substr",
+    "tier": "rare",
+    "task": "Substring by start index and LENGTH (deprecated)",
+    "call": "s.substr(start, length)",
+    "mutates": false,
+    "returns": "new string",
+    "signature": "s.substr(start, length)  // deprecated; use slice",
+    "example": "return 'abcdef'.substr(1,3);",
+    "expected": "\"bcd\"",
+    "gotcha": "Second arg is a length, not an end index. Deprecated."
+  },
+  {
+    "method": "concat",
+    "tier": "rare",
+    "task": "Concatenate strings with a method call",
+    "call": "s.concat(a, b)",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return 'a'.concat('b','c');",
+    "expected": "\"abc\"",
+    "gotcha": "Just use + or a template literal."
+  },
+  {
+    "method": "search",
+    "tier": "rare",
+    "task": "Find the index of a regex match",
+    "call": "s.search(/c/)",
+    "mutates": false,
+    "returns": "index, or -1",
+    "example": "return 'abc'.search(/c/);",
+    "expected": "2"
+  },
+  {
+    "method": "localeCompare",
+    "tier": "rare",
+    "task": "Compare two strings for sorting",
+    "call": "a.localeCompare(b)",
+    "mutates": false,
+    "returns": "negative / 0 / positive number",
+    "example": "return ['b','a','c'].sort((x,y)=>x.localeCompare(y));",
+    "expected": "[\"a\",\"b\",\"c\"]",
+    "gotcha": "Locale-aware and slower; for plain code-unit order use a < b ? -1 : 1."
+  },
+  {
+    "method": "codePointAt",
+    "tier": "rare",
+    "task": "Get the full Unicode code point at index i",
+    "call": "s.codePointAt(i)",
+    "mutates": false,
+    "returns": "number",
+    "example": "return '😀'.codePointAt(0);",
+    "expected": "128512",
+    "gotcha": "charCodeAt would return only half of the surrogate pair."
+  },
+  {
+    "method": "normalize",
+    "tier": "rare",
+    "task": "Normalize Unicode (e.g. strip accents with NFD)",
+    "call": "s.normalize('NFD')",
+    "mutates": false,
+    "returns": "new string",
+    "example": "return 'é'.normalize('NFD').length;",
+    "expected": "2"
+  }
 ]