TA貢獻(xiàn)1795條經(jīng)驗(yàn) 獲得超7個(gè)贊
wall_reply_text最可能的解釋是當(dāng)這段代碼運(yùn)行時(shí)沒有類名的元素，所以document.getElementsByClassName('wall_reply_text')返回一個(gè)空數(shù)組。當(dāng)您嘗試訪問該空數(shù)組中的索引 0 時(shí)，您會(huì)得到undefined，因此在嘗試訪問時(shí)會(huì)出現(xiàn)錯(cuò)誤undefined.textContent。
TA貢獻(xiàn)1871條經(jīng)驗(yàn) 獲得超13個(gè)贊
如果沒有元素，則需要中斷
var n = 0, comment=""
while (true) {
const div = document.getElementsByClassName('wall_reply_text')[n]
if (div) comment = div.textContent;
else break
if (comment.indexOf("публикации") == 0) {
console.log(n,comment);
}
n++;
}
<div class="wall_reply_text">1</div>
<div class="wall_reply_text">публикации</div>
<div class="wall_reply_text">3</div>
<div class="wall_reply_text">4</div>
這是一種更優(yōu)雅的方式
[...document.querySelectorAll('.wall_reply_text')]
.map(div => div.textContent)
.forEach((comment,i) => {
if (comment.indexOf("публикации") == 0) {
console.log(i,comment);
}
})
<div class="wall_reply_text">1</div>
<div class="wall_reply_text">публикации</div>
<div class="wall_reply_text">3</div>
<div class="wall_reply_text">публикации</div>
如果您只需要一個(gè)索引，則可以選擇
const comments = [...document.querySelectorAll('.wall_reply_text')]
.map(div => div.textContent)
console.log(comments.indexOf("публикации"))
<div class="wall_reply_text">1</div>
<div class="wall_reply_text">публикации</div>
<div class="wall_reply_text">3</div>
<div class="wall_reply_text">4</div>
舉報(bào)