如何首次將值存儲到瀏覽器 localStorage？

Question

在這里，我聲明了一個具有本地存儲值的變量var yourLink = parseInt(localStorage.getItem('linkID')); 但問題是當第一次沒有價值時這是行不通的。 因此，我嘗試在沒有找到值的情況下添加另一個if語句，然后為yourLink變量賦值。 但是做不到。 接下來我可以嘗試什么？

這里我給出完整的代碼：

var link = ["https://www.facebook.com/", "https://stackoverflow.com/"];


var yourLink = parseInt(localStorage.getItem('linkID'));



localStorage.setItem('linkID', yourLink);


if ((parseInt(localStorage.getItem('linkID')))<= 7 ) {
    yourLink = parseInt(localStorage.getItem('linkID')) + 1;
    localStorage.setItem('linkID', yourLink);

    yourLink = parseInt(localStorage.getItem('linkID'))

    window.open(link[0], '_blank');


} else if ((parseInt(localStorage.getItem('linkID'))) >= 8) {
    yourLink = parseInt(localStorage.getItem('linkID')) + 1;
    localStorage.setItem('linkID', yourLink);

    yourLink = parseInt(localStorage.getItem('linkID'))

    window.open(link[1], '_blank');

    yourLink = 0;
    localStorage.setItem('linkID', yourLink);
}

Answer 1

可以用這個條件判斷是否是第一次

if(localStorage.getItem('linkID') == null){
    // do your logic here
}

Answer 2

在您的問題中，數據在localStorage中設置為parseInt(localStorage.getItem('linkID'))任何時候都不會是NaN 。 所以你能做的是

var link = ["https://www.facebook.com/", "https://stackoverflow.com/"];

if(!localStorage.getItem('linkID')) {
   localStorage.setItem('linkID', 0);
}

if ((parseInt(localStorage.getItem('linkID')))<= 7 ) {
    yourLink = parseInt(localStorage.getItem('linkID')) + 1;
    localStorage.setItem('linkID', yourLink);

    yourLink = parseInt(localStorage.getItem('linkID'))

    window.open(link[0], '_blank');

} else if ((parseInt(localStorage.getItem('linkID'))) >= 8) {
    yourLink = parseInt(localStorage.getItem('linkID')) + 1;
    localStorage.setItem('linkID', yourLink);

    yourLink = parseInt(localStorage.getItem('linkID'))

    window.open(link[1], '_blank');

    yourLink = 0;
    localStorage.setItem('linkID', yourLink);
}

希望這有助於解決您的問題。