[英]JSON-array and forEach issue
所以...根据控制台,我遇到的问题是: “未捕获的 TypeError:无法读取 custom.js:42、Array.forEach ()、custom.js:39 处未定义的属性‘title’”
“标题”如何未定义? my.forEach 有什么问题? (悲伤的声音)
我构建的 JSON 数组中的六个对象中的第一个示例:
var newReleases = [
{
"title":"Honor - Defending the motherland",
"author":"Mark Thomas",
"genre":"Fiction",
"description":"In legislation and formal documents the suffix shire was generally not used: for example, Bedfordshire was referred to as the administrative county of Bedford and the Northamptonshire council as the county council of Northampton.The 1888 Act did not contain a list of administrative counties: it was not until 1933 and the passing of a new Local Government Act."},
For循环与forEach function:
for (var i = 0; i < 6; i++){
newReleases.forEach (function (newReleases) {
var bookTitle = document.getElementsByClassName('card-header')
var t = document.createTextNode(newReleases[i].title);
bookTitle.appendChild(t);
var bookAuthor = document.getElementsByClassName('card-title')
var a = document.createTextNode(newReleases[i].authors);
bookAuthor.appendChild(a);
var cardGenre = document.getElementsByClassName("card-subtitle");
var genre = document.createTextNode(newReleases[i].genre);
cardGenre.appendChild(genre);
var cardDescr = document.getElementsByClassName('card-text');
var p = document.createTextNode(newReleases[i].description);
cardDescr.appendChild(p);
}) //end of forEach
} // end of for-loop
使用for
或forEach()
之一,不能同时使用。
for (var i = 0; i < newReleases.length; i++) {
var bookTitle = document.getElementsByClassName('card-header')[0]
var t = document.createTextNode(newReleases[i].title);
bookTitle.appendChild(t);
var bookAuthor = document.getElementsByClassName('card-title')[0]
var a = document.createTextNode(newReleases[i].authors);
bookAuthor.appendChild(a);
var cardGenre = document.getElementsByClassName("card-subtitle")[0];
var genre = document.createTextNode(newReleases[i].genre);
cardGenre.appendChild(genre);
var cardDescr = document.getElementsByClassName('card-text')[0];
var p = document.createTextNode(newReleases[i].description);
cardDescr.appendChild(p);
}
要么
newReleases.forEach(function(release) {
var bookTitle = document.getElementsByClassName('card-header')[0]
var t = document.createTextNode(release.title);
bookTitle.appendChild(t);
var bookAuthor = document.getElementsByClassName('card-title')[0]
var a = document.createTextNode(release.authors);
bookAuthor.appendChild(a);
var cardGenre = document.getElementsByClassName("card-subtitle")[0];
var genre = document.createTextNode(release.genre);
cardGenre.appendChild(genre);
var cardDescr = document.getElementsByClassName('card-text')[0];
var p = document.createTextNode(release.description);
cardDescr.appendChild(p);
});
当你使用forEach()
时你不需要给数组变量下标,你只需要使用参数来回调 function。
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