Isifundo seJSON -Funda ukuba uyisebenzisa kanjani iJSON ngeJavaScript

Kule tutorial, siza kufunda malunga neJSON. Siza kugubungela ubume beJSON, iintlobo ezahlukeneyo zedatha kunye nendlela yokusebenzisa iJSON ngaphakathi kweJavaScript.

I-JSON yenye yezona zinto zibaluleke kakhulu onokuzifunda njengenkqubo okanye njenge-QA.

Kuwo wonke umsebenzi wakho weprogram uza kusebenzisa iJSON ngalo lonke ixesha nokuba iyenza i-API, isebenzisa i-API, okanye yenza iifayile zokumisela isicelo sakho.

Yintoni iJSON

IJSON emele ukuphawulwa kwento yeJavaScript, yifomathi yokumelwa kwedatha efana kakhulu neXML okanye iYAML.

Isetyenziswa ngokubanzi kwi-intanethi phantse kuyo yonke i-API enye oza kuyifumana, kunye neefayile zokumisela kunye nezinto ezinje ngemidlalo nabahleli bombhalo.

Umzekelo weJSON:

#user.json {
'name': 'Steve',
'age': 43,
'isProgrammer' true,
'hobbies': ['Reading Java books', 'cooking', 'classic music'],
'friends': [{
'name': 'joey',
'age': 39,
'isProgrammer': false,
'friends': [...]
}] }

Kutheni usebenzisa iJSON

Sisebenzisa iJSON kuba ilula kakhulu ukuthumela ukubuyela umva kwizicelo ze-http kunye neempendulo ngenxa yesayizi encinci yefayile.

Kulula ukufunda xa kuthelekiswa nento efana neXML kuba icocekile kakhulu kwaye akukho zininzi zokuvula nokuvala iithegi zokukhathazeka.

IJSON ikwadibanisa kakuhle kakhulu neJavaScript kuba iJSON sisiqwengana seJavaScript, oko kuthetha ukuba nantoni na oyibhalayo kwiJSON yiJavaScript esebenzayo.

Phantse zonke iilwimi eziphambili zineendlela ezithile zethala leencwadi okanye ezakhelweyo ekusebenziseni imitya yeJSON kwizinto okanye kwiiklasi kolo lwimi.

Oku kwenza ukusebenza kwedatha yeJSON kube lula kakhulu ngaphakathi kulwimi lwenkqubo.

Iindidi zeDatha yeJSON

Ngoku xa siqonda ukuba yintoni i-JSON kwaye kutheni kubalulekile, masingene kwezinye ze-syntax ezichaphazelekayo kunye neentlobo zedatha ezinokumelwa yiJSON.

Njengoko sisazi ukuba iJSON yifomathi yokumelwa kwedatha ngenxa yoko kufuneka sikwazi ukumela iintlobo ezithile zedatha ngaphakathi kuyo.

IJSON ngokwendabuko ixhasa:

• imitya
• amanani amanani angabakho nakweyiphi na ifomathi nokuba ngamanani edesimali amanani apheleleyo amanani amabi nkqu namanani okubhalwa kwesayensi
• Ndithathe ezinokuba ziyinyani okanye zibubuxoki
• Akukho nto engamele nto
• Ukufika enokuba luluhlu lazo naziphi na iintlobo ezingasentla
• Izinto into yeyona nto inzima kodwa olona hlobo lusetyenzisiweyo ngaphakathi kweJson njengoko ikuvumela ukuba ubonise idatha engamaxabiso abalulekileyo

Umzekelo weJSON

Masingene kumzekelo wendlela yokusebenzisa i-json ngaphakathi kwifayile.

Into yokuqala ekufuneka uyenzile kukwenza ifayile nge .json ulwandiso ekupheleni kwayo.

Siza kudala user.json ifayile enento yomsebenzisi emelwe njengeJSON.

Ukwenza into kufuneka sisebenzise ukuvula nokuvala ii-brace curly {} kwaye emva koko siyakubeka onke amaxabiso abalulekileyo abumba into yethu.

Yonke ipropathi enye ngaphakathi kweJSON sisibini sexabiso. Isitshixo kufuneka singqongwe kabini '' iikowuti ezilandelwa yikholoni : kunye nexabiso lesitshixo.

Ukuba sinezibini ezininzi zexabiso eliphambili, sifuna ii-commas , Ukwahlula nganye nganye kwiipini zethu zexabiso eliphambili, ngokufanayo nendlela esinokulwenza ngayo uluhlu kulwimi oluqhelekileyo lwenkqubo.

Umzekelo Ifayile yeJSON

#user.json {
'name': 'Steve',
'age': 43,
'isProgrammer' true,
'hobbies': ['Reading Java books', 'cooking', 'classic music'],
'friends': [{
'name': 'joey',
'age': 39,
'isProgrammer': false,
'friends': [...]
}] }

Kumzekelo ongentla, sinefayile ebizwa user.json. Ngaphakathi kwifayile sineentlobo ezahlukeneyo zedatha.

Izitshixo zihlala zijikelezwe kukucaphula kabini. Kumaxabiso, luhlobo lomtya kuphela olujikelezwe ziicaphuli eziphindwe kabini.

Kumzekelo:

• Igama | | + _ |
• ubudala string
• Inkqubo yenkqubo integer
• zokuzonwabisa yi boolean
• Abahlobo yi Array

Phawula:Akukho comma ekupheleni kwepropathi yokugqibela kwifayile yeJSON okanye into yeJSON.

Uyisebenzisa kanjani iJSON String ngaphakathi kweJavaScript

Masicinge ukuba sinefayile yeJSON ebizwa Array of Objects Uluhlu lwezinto zenkampani:

companies.json

Kumzekelo ongentla, sinezinto ezimbini zenkampani ngaphakathi kuluhlu lweJSON.

Ngoku makhe sijonge ukuba singayisebenzisa njani le JSON ingentla ngaphakathi kweJavaScript.

Kwiimeko ezininzi, sifumana iJSON njengomtya kunokuba ibe yinto yeJSON. Ukulinganisa oku, simele le JSON ingasentla njengomtya ngaphakathi kweJavaScript.

Ifayile yethu ye-html ijongeka ngathi:

[
{
'name': 'Big corporate',
'numberOfEmployees': 1000,
'ceo': 'Neil',
'rating': 3.6
},
{
'name': 'Small startup',
'numberOfEmployees': 10,
'ceo': null,
'rating': 4.3
} ]

Xa sihlola ilog yekhonkco kwizixhobo zonjiniyela zeChannel, iziphumo ziyafana noko kuboniswe ngezantsi:

Emva koko sinokubonisa iJSON engasentla ngokuchaza into esifuna ukuyikhupha. Umzekelo, ukuba sifuna ukufumana igama lenkampani yokuqala kuludwe esinokulusebenzisa:


JSON Example

let companies =
`[
{

'name': 'Big corporate',

'numberOfEmployees': 1000,

'ceo': 'Neil',

'rating': 3.6
},
{

'name': 'Small startup',

'numberOfEmployees': 10,

'ceo': null,

'rating': 4.3
}
]`
console.log(JSON.parse(companies))


Ngokunjalo, ukufumana inqanaba lenkampani yesibini esinokuyisebenzisa:

console.log(JSON.parse(
companies[0].name )) Output: Big corporate

Ungayiguqula njani into yeJavaScript kwiJSON

Ngoku masithi sinento yeJavaScript efana nale iboniswe ngezantsi:

console.log(JSON.parse(
companies[1].rating )) Output: 4.3

Ukuguqula into yeJavaScript ibe yiJSON sisebenzisa
JSON Example

var person = {
name: 'Brad',
age: 35
}
indlela:

stringify

Iziphumo yiJSON esebenzayo:

jsonPerson = JSON.stringify(person); Phawula:{
'name': 'Brad',
'age': 35 } ishicilela IsiNgesi . Ukufumana ixabiso, kufuneka siguqule iJSON ibuyele kwinto yeJavaScript.

Ukwenza lo msebenzi ungasentla, kufuneka siguqule iJSON ibuyele kwinto yeJavaScript.

Ungayiguqula njani into yeJSON kwiJavaScript

Ukuguqula into engentla yeJSON ibuyisele kwiJavaScript, sisebenzisa console.log(jsonPerson.name) indlela:

parsePhawula:Ngoku ukuba sizamile jsPerson = JSON.parse(jsonPerson) sifumana 'uBrad'.

Umzekelo opheleleyo

console.log(jsPerson.name)

Isishwankathelo

• UJSON umele iNqaku leNqaku leJavaScript
• Ifomathi yokutshintshiselana ngedatha elula
• Ngokusekwe kwiseti esezantsi yeJavaScript
• Kulula ukufunda nokubhala
• Ulwimi oluzimeleyo
• Inokudityaniswa kwiilwimi ezininzi zangoku

Iindidi zedatha:

• Inombolo: Akukho mahluko phakathi kwenani elipheleleyo kunye nokudada
• Umtya: Umtya wabalinganiswa be-Unicode. Sebenzisa iikowuti eziphindiweyo
• Boolean: Nyani okanye UBUXOKI
• Uluhlu: Uluhlu olu-odolwe nge-0 okanye amaxabiso angaphezulu kwi
JSON Example

var person = {
name: 'Brad',
age: 35
}
jsonPerson = JSON.stringify(person); //convert to JSON
console.log(jsonPerson.name); //undefined
jsPerson = JSON.parse(jsonPerson); //convert to JS Object
console.log(jsPerson.name); //Brad

• Into: Ukuqokelelwa okungalawulekiyo kwezibini eziphambili / zexabiso
• Akukho nto: Ixabiso elingenanto

Imigaqo yeJSON Syntax:

• Sebenzisa izitshixo / ixabiso lezibini- umz. []
• Sebenzisa iikowuti eziphindwe kabini KEY
• Kufuneka usebenzise iintlobo zeedatha ezichaziweyo
• Uhlobo lwefayile ngu .json
• Uhlobo lwe-MIME ngu “Application / json”

Ndiyathemba ukuba uyifumene le tutorial yeJSON ngeJavascript eluncedo. Ngoku ungabhala iifayile ezilula nezintsokothileyo zeJSON kwaye unxibelelane nentambo yeJSON ngaphakathi kweJavaScript.