Question

我是编程的新手，我正在尝试使用Javascript编写待办事项列表并尝试使用JQuery。我在网上找到了一个删除线的动画，我想在列表中实现，但我不太清楚这两行代码是做什么的，并且想知道是否有人可以为我详细说明，以便我能更好地理解？删除线功能如下：

@Data
@NoArgsConstructor
@Entity
@Immutable
@Table(name = "MY_ORDER", schema = "Data")
public class MyOrder implements Serializable {

@Id
@Column(name = "ORD_ID")
private Integer orderId;

@NonNull
@Column(name = "APP_NAME")
private String appName;
@NonNull
@Column(name = "ORD_NUM")
private String orderNumber;

@ManyToOne
@JoinColumn(name = "STO_ID")
private Store store;

@OneToOne
@JoinColumns({
        @JoinColumn(name = "APP_NAME", referencedColumnName = "APP_NAME", insertable = false, updatable = false),
        @JoinColumn(name = "ORD_NUM", referencedColumnName = "ORD_NUM", insertable = false, updatable = false)})
@org.hibernate.annotations.ForeignKey(name = "none")
private Tender tender;

@OneToMany
@JoinTable(
        name = "TX_to_MY_ORDER", schema = "Data",
        joinColumns = { // note X_to_MY_ORDER.ORD_NO vs. ORD_NUM
                @JoinColumn(name = "APP_NAM", referencedColumnName = "APP_NAM", insertable = false, updatable = false),
                @JoinColumn(name = "ORD_NO", referencedColumnName = "ORD_NUM", insertable = false, updatable = false)},
        inverseJoinColumns = {@JoinColumn(name = "TRN_NO", insertable = false, updatable = false)})
@org.hibernate.annotations.ForeignKey(name = "none")
private Set<Transaction> transactions;

/**
 * Because APP_NAM and ORD_NUM are not foreign keys to TX_TO_MY_ORDER (and they shouldn't be),
 * Hibernate 5.x saves this toString() as the 'owner' key of the transactions collection such that
 * it then appears in the transactions collection's own .toString(). Lombok's default generated
 * toString() includes this.getTransactions().toString(), which causes an infinite recursive loop.
 * @return a string that is unique per order
 */
@Override
public String toString() {
    // use appName + orderNumber since, as they are the columns used in the join, they must (?) have
    // already been set when attaching the transactions - primary key sometimes isn't set yet.
    return this.appName + "\00" + this.orderNumber;
}
}

我困惑的两条线是：

//var _Text sets the _Text to the individual list item
var _text = document.getElementById("item_" + cbId); 
$(document).ready(function() {
_text = $(itemText).text();
StrikeThrough(0);
});
//Strikethrough animation function
function StrikeThrough(index) {
    if (index >= _text.length)
        return false;
    var sToStrike = _text.substr(0, index + 1);
    var sAfter = (index < (_text.length - 1)) ? _text.substr(index + 1, 
_text.length - index) : "";
    $(itemText).html("<strike>" + sToStrike + "</strike>" + sAfter);
    window.setTimeout(function() {
        StrikeThrough(index + 1);
    }, 100);

我特别困惑的是这些变量被准确设置为什么

Answer 1

sToStrike设置为从当前索引位置的开头到下一个字符的文本如果索引不是最后一个字符

，则sAfter设置字符串的其余部分

Answer 2

此行将sToStrike的子字符串从索引_text分配给0索引index + 1：

var sToStrike = _text.substr(0, index + 1);

这一行包含一个三元表达式，它是一个内联if / else。它将sAfter的子字符串从索引_text分配给索引index + 1或空字符串_text.length - index依赖于""评估为True或错误，按各自的顺序排列：

index < (_text.length-1)

这些代码行做了什么？

2 个答案: