console 命令行工具 X clear

console

"use strict"
var obj = {}
Object.defineProperty(obj, 'year', {
    configurable: false,
    value: 2
})
var proxy = new Proxy(obj, {
    has: function(target, prop) {
        console.log('called: ' + prop);
        return false;
    }
})
console.log('year' in proxy); // Uncaught TypeError: 'has' on proxy: trap returned falsish for property 'year' which exists in the proxy target as non-configurable

<! DOCTYPE html>
<html>
    <body>
        target的某属性为不可配置，则该属性不能被代理隐藏（即handle.has不能返回false） 
    </body>
</html>