[英]Set Trap execute for two times - JS Proxy
Im working with proxies in js, but something is weird =>我在 js 中使用代理,但有些东西很奇怪 =>
let _usernames = [];
_usernames = new Proxy(_usernames, {
set(target, prop, val) {
console.count(); //this execute for two times!
if(typeof val === 'string') {
target[prop] = val;
return true;
} else {
return false;
}
}
});
_usernames.push('Manuel');
The Set
trap should call only once when i push to the array, but it executed twice.当我推送到数组时,
Set
陷阱应该只调用一次,但它执行了两次。
And there is an error in the console, when i push to array =>当我推送到数组时,控制台出现错误 =>
Uncaught TypeError: proxy set handler returned false for property '"length"'
How can i fix this and what's wrong?我该如何解决这个问题?出了什么问题?
Calling Array#push
causes set
to be called two times:调用
Array#push
会导致set
被调用两次:
In your case, the second call is returning false since the length value is numeric.在您的情况下,第二次调用返回 false,因为长度值是数字。
A possible solution:一个可能的解决方案:
let _usernames = []; _usernames = new Proxy(_usernames, { set(target, prop, val) { console.log(target, prop, val); if(typeof val === 'string' || prop === 'length') { target[prop] = val; return true; } else { return false; } } }); _usernames.push('Manuel');
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