Javascriptæååã®ã¡ãœãã : slice(), substring(), includes(), startsWith(), trim(), replace()…….
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ã§ã¯ãé »ç¹ã«äœ¿ãã¡ãœããã®äžslice(), substring(), includes(), startsWith(), trim(), replace(), indexOf(), test()ãã玹ä»ããŸãã
sliceã¡ãœããã¯ã€ã³ããã¯ã¹ããã©ã¡ãŒã¿ã§æž¡ããå¿
èŠãªæååãæœåºããŸãã
ã¹ã¿ãŒãã€ã³ããã¯ã¹(start index)ãšçµäºã€ã³ããã¯ã¹(end indexãçç¥å¯)ãæž¡ããçµäºã€ã³ããã¯ã¹ãçç¥ããå Žåã¯æååã®æåŸãŸã§ã«ãªããŸãã
ãã©ã¡ãŒã¿ãïŒã®å Žåã¯é ããäžçªç®ã-1ã¯éã§åŸãããäžçªç®ã®æå³ã«ãªããŸãã
const myWord = 'primavera';
myWord.slice(0,5); // 'prima'
myWord.slice(-4); // 'vera'
myWord.slice(3); // 'mavera'
myWord.slice(3,1); // '' -> slice()ã¯ã¹ã¿ãŒããçµäºãã倧ãããšç©ºãè¿ã
substringã¡ãœãããsliceãšåããã€ã³ããã¯ã¹ãæž¡ããæååãæœåºããŸãã
åºæ¬çãªæäœã¯åæ§ã§ããsubstringã¯ã¹ã¿ãŒããçµäºãã倧ããã®å Žåèªåã«äœçœ®ã亀æããŠã¡ãœããã宿œããŸãã
ãŸããsubstringã«è² æ°ãå
¥ãããšïŒãšèªèããŸãã
äŸãã°(3, -1)ãæž¡ããš(3, 0)ãšããŠèªèããŸããããã«(3, 0)ã¯ã¹ã¿ãŒãã倧ããã®ã§èªå亀æãã(0, 3)ã宿œããŸãã
ã¡ãœããåã䌌ããããªsubstrã¯âäœçœ®âãšâæåæ°’ããã©ã¡ãŒã¿ã«æž¡ãã¡ãœããã§ãã
const myWord = 'invierno';
myWord.substring(3); // 'ierno'
myWord.substring(1,3); // 'nv'
myWord.substring(3,1); // 'nv' -> èªåã«ã¹ã¿ãŒããšçµäºäœçœ®äº€æ
myWord.substring(3,-1); // 'inv' -> è² æ°ã¯0, èªåäœçœ®äº€æ
myWord.substring(-4); // 'invierno' -> è² æ°ã¯0, ã¹ã¿ãŒã(0)ããæåŸãŸã§
myWord.substr(1,3); // 'nvi' -> ã¹ã¿ãŒã1ããäžã€
includesã¯æååã®äžãæå®ããæååãå«ãŸããŠãããããã§ãã¯ããŸãã
ãã©ã¡ãŒã¿ã¯æåå (å¿
é )ãšã€ã³ããã¯ã¹(çç¥å¯)ãæž¡ããè¿ãã®ã¯trueæã¯falseã§ãã
ãã®ã¡ãœããã¯æå®æåã¯ãã¡ãããé
åã®äžã§ç©ºã®å€ã確èªããããã«ã¯äœ¿ããŸãã
const myWord = 'alegria';
myWord.includes('le'); // true
myWord.includes('i'); // true
myWord.includes('rio'); // false
const myArray = ['dream','','king'];
myArray.includes(''); // true -> myArray[1]ã空ãªã®ã§true
myArray.includes('dream'); // true -> myArray[0]ãšäžèŽ
myArray.includes('drea'); // false -> èŠçŽ ã¯å®å
šäžèŽããå Žåã®ã¿true
startsWithã¡ãœãããæååãå«ãŸããŠãããããã§ãã¯ããŸãã
æååã®ã¿æž¡ããš0ã€ã³ããã¯ã¹ããå§ãŸãæå®æåã®ååšã確èªããBOOLEANãè¿ããŸãã
endsWithã¯æå®æåã§çµããããšããã§ãã¯ããŸãã
const mySentence = 'cafe con leche';
mySentence.startsWith('cafe'); // true
mySentence.startsWith('fe'); // false
mySentence.startsWith('fe',2); // true
mySentence.endsWith('eche'); // true
trimã¯æååäž¡æã®ç©ºçœãé€ãã¡ãœããã§ãã
æåå倿ã®éçšã§å
¥ããã空çœãŸãã¯ã¿ã€ããã¹ã§å
¥ã£ãæååã¯æåæ¯èŒã®æfalseãè¿ãããšã©ãŒã«ãªããã¡ã§ãã
ãªã®ã§trimã§ç©ºçœãäºåã«é€ãããšã©ãŒãäºé²ããããšãã§ããŸãã
æååäž¡æã®ç©ºçœãã¿ãããæ¹è¡(/n)æåãé€ãããšãã§ããŸãããäž¡æã§ã¯ãªãæååäžã«å
¥ã£ãŠããã®ã¯äœåããŸããã
const mySentence = ' la casa de papel ';
mySentence.trim(); // 'la casa de papel'
const mySentence = ' el amor \n';
mySentence.trim(); // 'el amor'
replaceã¯æååããæå®ããæåãæ¢ããŠå€ææåã«å€æããŸãã
æååã®äžã«æå®æåãäžã€ä»¥äžååšãããšããæåã«èŠåœããã®ã ãã倿Žå¯Ÿè±¡ã«ãªããŸãã
äŸãã° ‘my_name_is_Ron’ããã¢ã³ããŒããŒãå
šéšç©ºçœã«ããããreplace(‘_’,’ ‘)ã«ããŠãçµæã¯âmy name_is_Ron’ã«ãªããŸãã
ãªã®ã§ãæååã®äžã§ååšããå
šãŠãæå®æåã倿ãããæã¯æ£èŠè¡šçŸ ã䜿ããšè¡ããŸãã
const mySentence = 'my name is:Ron';
mySentence.replace(':',' '); //'my name is Ron'
const mySentence = 'my_name_is_Ron';
mySentence.replace('_',' '); // 'my name_is_Ron'
//æ£èŠè¡šçŸã§ãã¹ãŠã®æåã倿
mySentence.replace(/_/g, ' '); // 'my name is Ron'
indexOfã¯æå®æåã®äœçœ®ãè¿ããŸãã
ãã®ã¡ãœããã¯æå®æåã®åãŸãã¯åŸã§æååãåãåããšãæçšãªãã®ã§ãã
ããšãã’Z001-03’ããåŸãã®’03’ã ããæœåºããããšããindexOfã§’-‘æåãæ¢ããè¿ãã®index +1äœçœ®ããæåŸãŸã§ã«ãããããš’03’ãåãåãããšãã§ããŸãã
ããæååã®äžæå®æåãäžã€ä»¥äžã®å Žåãé ããæ¢ãå§ãæåã«èŠåœããæåäœçœ®ãè¿ããŸãã
ã§ããã©ã¡ãŒã¿ã«indexãæž¡ããšæå®ãããäœçœ®ããæå®æåãæ¢ããŸãã
泚æç¹ã¯start indexãæž¡ããŠãè¿ãå€ã¯å
šäœã®æååããäœçªç®ã§ãããšããæ°åãè¿ããŸãã
åŸãããæ€çŽ¢ããã®ã¯lastIndexOfã§ãåŸãããæåã®æå®æåã®äœçœ®ãè¿ããŸãã
ãã®æãè¿ãå€ã¯é ããäœçªç®ã§ãããšããæ°åã§ãã
æå®æåããªããã°-1ãè¿ããŸãã
const mySentence = 'Z001-03';
mySentence.indexOf('-'); // 4
mySentence.substring(mySentence.indexOf('-')+1); // '03'
mySentence.indexOf('D'); // -1
const mySentence = 'Z001-03-02';
mySentence.indexOf('-'); // 4
mySentence.indexOf('-', 5); // 7
mySentence.lastIndexOf('-') // 7
testã¯äžè¬çã«æ£èŠè¡šçŸãšäžç·ã«äœ¿ããæž¡ãæååãšæ¯èŒãæå¹æ§ã確èªããŸãã
ãã¹ã¯ãŒããã¢ã«ãã¡ããããç¹æ®æåãçå¹Žææ¥ãªã©ã®åœ¢åŒæ€æ»ã«äœ¿ããŸãã
const mySentence = /a/;
const myWord = 'baby';
mySentence.test(myWord); // true
/\d/.test('cookie'); // false \dã¯æ°åãæå³(æ£èŠè¡šçŸ)
/\d/.test('cookie1'); // true
äžã®äŸä»¥å€ã«ãå±±ã»ã©ã¡ãœãããå€ããããŸãæ°ããäœãããã¡ãœããããããããããŸããã
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