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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript Map.size 属性</h1>
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<p>Map.size 属性返回 Map 中元素的数量</p>
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<pre id="demo"></pre>
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<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();
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// Add new Elements to the Map
fruits.set(apples, 500);
fruits.set(bananas, 300);
fruits.set(oranges, 200);
​
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document.getElementById("demo").innerHTML = "当前Map对象有 " + fruits.size + " 个元素";
</script>
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</body>
</html>