• 如果数组中检测到有一个元素不满足，则整个表达式返回 false ，且剩余的元素不会再进行检测。
• 如果所有元素都满足条件，则返回 true。

注意： every() 不会对空数组进行检测。

注意： every() 不会改变原始数组。

例子：

var ages = [32, 33, 16, 40];
function checkAdult(age) {
    return age >= 18;
}
function myFunction() {
    document.getElementById("demo").innerhtml = ages.every(checkAdult);
}
 
false  输出结果

<button onclick="numbers.forEach(myFunction)">点我</button>
<p id="demo"></p>
 
<script>
demoP = document.getElementById("demo");
var numbers = [4, 9, 16, 25];
 
function myFunction(item, index) {
    demoP.innerHTML = demoP.innerHTML + "index[" + index + "]: " + item + "<br>"; 
}
</script>

输出结果
index[0]: 4
index[1]: 9
index[2]: 16
index[3]: 25

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.indexOf("Apple");

结果 2

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var energy = fruits.join();
结果
Banana,Orange,Apple,Mango

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.lastIndexOf("Apple");
结果 2

var numbers = [4, 9, 16, 25];

function myFunction() {
    x = document.getElementById("demo")
    x.innerHTML = numbers.map(Math.sqrt);
}
结果  2,3,4,5

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.pop();
返回  Banana,Orange,Apple

var numbers = [65, 44, 12, 4];
 
function getSum(total, num) {
    return total + num;
}
function myFunction(item) {
    document.getElementById("demo").innerHTML = numbers.reduceRight(getSum);
}
输出结果 125

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.reverse();
输出结果
Mango,Apple,Orange,Banana

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.shift()
结果
Orange,Apple,Mango

var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
var citrus = fruits.slice(1,3);
结果输出  Orange,Lemon

var ages = [3, 10, 18, 20];

function checkAdult(age) {
    return age >= 18;
}

function myFunction() {
    document.getElementById("demo").innerHTML = ages.some(checkAdult);
}
输出结果 true

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort();
输出结果 Apple,Banana,Mango,Orange

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(2,0,"Lemon","Kiwi");
输出结果  Banana,Orange,Lemon,Kiwi,Apple,Mango

var d=new Date();
var n=d.toLocaleString();
输出结果 2019/11/7 下午4:59:41

var d=new Date();
var n=d.toString();
Thu Nov 07 2019 17:00:09 GMT+0800 (中国标准时间)