NaN而不是數字我的加載問題

Question

我試圖創建一個代碼，每次加載組件時增加2％，但不是顯示該數字增量，我得到NaN。這是爲什麼？

//Define variable 
var PercentLoaded = 0; 

//When a component loads 
var PercentLoaded = PercentLoaded+2; 
//Print value 
$('#LoadProgressMessage').html('<h6>'+ PercentLoaded + '% Loaded</h6>'); 

感謝您的幫助！

Answer 1

儘量不要當你增加它重新聲明你的變量：

//Define variable 
var PercentLoaded = 0; 

//When a component loads 
/*var*/ PercentLoaded = PercentLoaded + 2; 

Answer 2

最有可能的變量不再在範圍內。您提供的代碼應該工作正常的本身，而是你可能在實際的代碼是這樣的：顯示

$(function() { 
    var PercentLoaded = 0; 

    // PercentLoaded is in scope only up to here 
}); 

function whatever() { 
    var PercentLoaded = PercentLoaded + 2; 
    // The original PercentLoaded is no longer in scope 
}