JavaScript拆分返回未定义

Question

我想知道是否有人可以帮助我并解释为什么，当我分割我的innerText时，它有时返回undefined并且是否有人可以指出正确的方向来解决这个问题

 var elems = document.getElementsByClassName("hud-leaderboard-party"), counter = elems.length, arrayLength = 0, maxLengthArray = 0; // LEADERBOARD NAMES window.leaderboardNames = function() { var Elem; if (counter <= 0) counter = elems.length; Elem = elems[counter - 1]; document.getElementsByClassName("hud-intro-name")[0].value = Elem.innerText.split("—")[0].split(",")[arrayLength]; maxLengthArray = Elem.innerText.split("—")[0].split(",").length; if (maxLengthArray == arrayLength) { arrayLength = 0; counter--; } else { arrayLength++; } } 

 <div class="hud-intro-leaderboard"> <div class="hud-intro-leaderboard-parties"> <div class="hud-leaderboard-party">Player name here 1, Player name here 2, Player name here 3, Player name here 4 — <strong>998</strong></div> <div class="hud-leaderboard-party">Player name here 5, Player name here 6, Player name here 7 — <strong>707</strong></div> <div class="hud-leaderboard-party">Player name here 8, Player name here 9, Player name here 10 — <strong>610</strong></div> <div class="hud-leaderboard-party">Player name here 11, Player name here 12 — <strong>448</strong></div> <div class="hud-leaderboard-party">Player name here 13, Player name here 14, Player name here 15, Player name here 16 — <strong>409</strong></div> </div> </div> <br><br> <button class="btn btn-green" style="width: 90%;" onclick="leaderboardNames();">LEADERBOARD NAMES</button> <br><br> <input type="text" class="hud-intro-name" style="width: 90%;" maxlength="29" placeholder="Your nickname"> 

Answer 1

如果-之后的值没有，则会发生未定义的情况，

所以在声明中

Elem.innerText.split("—")[0].split(",")[arrayLength];

你需要先检查

Elem.innerText.split("—")[0].split(",")

并安全地从中提取。

Answer 2

在您的arrayLength检查中发出，必须为+1

 let elems = document.getElementsByClassName("hud-leaderboard-party"), counter = elems.length, arrayLength = 0, maxLengthArray = 0; // LEADERBOARD NAMES window.leaderboardNames = function() { let elem; if (counter <= 0) { console.log(counter); counter = elems.length; } elem = elems[counter - 1]; let elemNames = elem.innerText.split("—")[0].split(','); document.querySelector(".hud-intro-name").value = elemNames[arrayLength]; maxLengthArray = elem.innerText.split("—")[0].split(",").length; if (maxLengthArray == arrayLength+1) { arrayLength = 0; counter--; } else { arrayLength++; } } 

 <div class="hud-intro-leaderboard"> <div class="hud-intro-leaderboard-parties"> <div class="hud-leaderboard-party">⋘TC⋙ ƘƠƦƘƲƧƲȤ, ƬƇ☢☠ⓀⓊⓇⓉ☠☢, ⋘TC⋙ ƘƠƦƘƲƧƲȤ, ƬƇ☢☠ⓀⓊⓇⓉ☠☢ — <strong>998</strong></div> <div class="hud-leaderboard-party">Sweet Heart TW, High Score GO!, High Score GO! — <strong>707</strong></div> <div class="hud-leaderboard-party">K¥LË, K¥LË3, This has been removed, This has been removed — <strong>610</strong></div> <div class="hud-leaderboard-party">Exxotic, ภคŦғเค :P... (MSR), Hauzz✔️ — <strong>448</strong></div> <div class="hud-leaderboard-party">Brightstar, Yaslin, Yaslin, Yaslin — <strong>409</strong></div> </div> </div> <br><br> <button class="btn btn-green" style="width: 90%;" onclick="leaderboardNames();">LEADERBOARD NAMES</button> <br><br> <input type="text" class="hud-intro-name" style="width: 90%;" maxlength="29" placeholder="Your nickname">