给定一个JavaScript对象, 任务是获取JavaScript对象的最后一个元素。
方法1:
- 采用Object.keys()方法获取对象的所有键。
- 现在, 使用索引来访问JavaScript对象的最后一个元素。
例子:本示例实现了上述方法。
<!DOCTYPE HTML>
< html >
< head >
< title >
How to get the last item
of JavaScript object ?
</ title >
</ head >
< body style = "text-align:center;" >
< h1 style = "color:green;" >
lsbin
</ h1 >
< p id = "GFG_UP1" style =
"font-size: 15px; font-weight: bold;" >
</ p >
< p id = "GFG_UP2" style = "font-size: 15px;
font-weight: bold; color: green;">
</ p >
< button onclick = "GFG_Fun()" >
click here
</ button >
< p id = "GFG_DOWN" style = "color:green;
font-size: 20px; font-weight: bold;">
</ p >
< script >
var up1 = document.getElementById('GFG_UP1');
var up2 = document.getElementById('GFG_UP2');
var down = document.getElementById('GFG_DOWN');
var Obj = {
"1_prop": "1_Val", "2_prop": "2_Val", "3_prop": "3_Val"
};
up1.innerHTML = "Click on the button to get"
+ "the last element of the Object.";
up2.innerHTML = JSON.stringify(Obj);
function GFG_Fun() {
down.innerHTML = "The last key = '" +
Object.keys(Obj)[Object.keys(Obj).length-1]
+ "' < br > Value = '"
+ Obj[Object.keys(Obj)[Object.keys(Obj).length-1]]
+ "'";
}
</ script >
</ body >
</ html >
输出如下:
在单击按钮之前:
单击按钮后:
方法二:
- 采用for循环要访问对象的所有键, 则在循环结束时, 循环变量将具有对象的最后一个键。
- 现在, 使用索引来访问JavaScript对象的最后一个元素的值。
例子:本示例实现了上述方法。
<!DOCTYPE HTML>
< html >
< head >
< title >
How to get the last item
of JavaScript object ?
</ title >
</ head >
< body style = "text-align:center;" >
< h1 style = "color:green;" >
lsbin
</ h1 >
< p id = "GFG_UP1" style =
"font-size: 15px; font-weight: bold;" >
</ p >
< p id = "GFG_UP2" style = "font-size: 15px;
font-weight: bold; color: green;">
</ p >
< button onclick = "GFG_Fun()" >
click here
</ button >
< p id = "GFG_DOWN" style = "color:green;
font-size: 20px; font-weight: bold;">
</ p >
< script >
var up1 = document.getElementById('GFG_UP1');
var up2 = document.getElementById('GFG_UP2');
var down = document.getElementById('GFG_DOWN');
var Obj = {
"1_prop": "1_Val", "2_prop": "2_Val", "3_prop": "3_Val"
};
up1.innerHTML = "Click on the button to get"
+ "the last element of the Object.";
up2.innerHTML = JSON.stringify(Obj);
function GFG_Fun() {
var lastElement;
for (lastElement in Obj);
lastElement;
down.innerHTML = "The last key = '" +
lastElement + "' < br > Value = '"
+ Obj[lastElement] + "'";
}
</ script >
</ body >
</ html >
输出如下:
在单击按钮之前:
单击按钮后: