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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript Map.has() 方法</h1>
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<p>Map.has() 检查 Map 中是否存在指定元素</p>
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<p id="demo"></p>
​
<script>
// 创建对象
const apples = {name: 'Apples'};
const bananas = {name: 'Bananas'};
const oranges = {name: 'Oranges'};
​
// 创建新的 Map
const fruits = new Map();
​
// Add new Elements to the Map
fruits.set(apples, 500);
fruits.set(bananas, 300);
fruits.set(oranges, 200);
​
​
​
if( fruits.has(apples) )
{
    document.getElementById("demo").innerHTML = "水果中包含苹果";
}
else
{
    document.getElementById("demo").innerHTML = "水果中不包含苹果";
}
</script>
​
</body>
</html>