Babban matsala tare da bincika idan akwai canji shine yana iya zama a hankali.
if (typeof variable !== 'undefined') {
// the variable is defined
}
Layin farko shine idan sanarwa. Yana bincika idan nau'in canjin ba daidai yake da 'undefined' ba. Idan ba haka ba, to yana gudanar da lambar a cikin takalmin gyaran kafa. Wannan lambar kawai tana buga saƙo yana cewa an ayyana maɓalli.
Idan akwai hanya
Hanyar IfExists aikin ginannen aiki ne a cikin JavaScript wanda ke dubawa don ganin ko ƙayyadadden yanayin gaskiya ne. Idan haka ne, aikin yana dawo da ƙima; in ba haka ba, ya koma banza.
masu canji da madaukai
A cikin JavaScript, ana bayyana masu canji ta amfani da kalmar var kuma ana iya sanya ƙima ta amfani da = afareta. Ana ƙirƙira madaukai ta amfani da sanarwa kuma ana iya amfani da su don maimaita saitin lamba ta takamaiman adadin lokuta.
