Question

我正在学习如何为Web开发做代码，而且我遇到了一个问题。两行几乎完全相同的代码给了我不同的结果：

for(i=0; i<=lunarSpells.length; i++){
    document.getElementById(lunarSpells[i]).innerHTML =
    Math.ceil(xpLeft/document.getElementById(lunarSpells[i]+"XP").innerHTML);   
}
for(i=0; i<=standardSpells.length; i++){
    document.getElementById(standardSpells[i]).innerHTML =
    Math.ceil(xpLeft/document.getElementById(standardSpells[i]+"XP").innerHTML);    
}

不确定它的重要性，但想法是从数组中取一个元素，在文档中找到它，然后相应地填写表格。这是阵列：

var lunarSpells = ["cureOther", "NPCContact", "curePlant", "monsterExamine", "bakePie", "cureMe", "TGMoonclan",
                            "TPMoonclan", "TGBarbarian", "superglass", "TPKhazard", "TGKhazard", "dream", "stringJewellery",
                            "statRestorePotShare", "statSpy", "TPBarbarian", "TPWaterbirth", "cureGroup", "TGWaterbirth", "humidify",
                            "hunterKit", "fertileSoil", "plankMake", "TPCatherby", "TGFishingGuild", "TGCatherby", 
                            "boostPotionShare", "TPIcePlateau", "energyTransfer", "healOther", "TGIcePlateau", "vengeanceOther",
                            "vengeance", "healGroup", "spellbookSwap", "magicImbue", "TPFishingGuild"]

var standardSpells = ["confuse", "sapphire", "weaken", "bananas", "curse", "lowAlch", "TPVarrock", "emerald", "TPLumbridge", "TPFalador", "TPHouse",
                                "superheat", "TPCamelot", "ruby", "TPArdougne", "highAlch", "earth", "water", "diamond", "TPWatchtower", 
                                "peaches", "TPTrollheim", "fire", "TPApe", "vulnerability", "air", "dragonstone", "enfeeble", "TOLumbridge", "stun", 
                                "TOFalador", "onyx", "TOCamelot"]

所以我的问题是，为什么lunarspells变量工作，而standardspells变量不是？任何帮助都非常感谢，因为我还是HTML和JS的新手。

Answer 1

如前所述：

xpLeft/document.getElementById(lunarSpells[i]+"XP").innerHTML

如果document.getElementById("id_that_doesnt_exist")评估为null，则

将失败（因为null.anything是错误。

这将停止<script>块中的所有进一步处理，除非您避免错误，或包裹在try / catch。

所以你的第二个循环将无法到达/执行。

两个几乎完全相同的代码行，结果不同？

1 个答案: