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1.8 KiB
1.8 KiB
title, localeTitle
| title | localeTitle |
|---|---|
| With | 同 |
同
JavaScript的with语句是在一个对象上编辑多个属性的简便方法。大多数开发人员不鼓励使用with ，您最好不要使用此关键字。
注意 ： "strict mode"禁止使用with 。
句法
with (expression)
statement
示例用法
在JavaScript中，您可以单独修改对象的属性，如下所示：
let earth = {};
earth.moons = 1;
earth.continents = 7;
with为您提供了修改对象属性的简写：
with (earth) {
moons = 1;
continents = 7;
}
虽然这个例子很做作，你能理解的用例with更多，如果你有更大的物体象下面这样：
earth.continents.australia.geography.ocean = "Pacific";
earth.continents.australia.geography.river = "Murray";
earth.continents.australia.geography.mountain = "Kosciuszko";
备择方案
你不应该使用它with因为它有微妙的错误和兼容性问题。强烈推荐的方法是将对象分配给变量，然后修改变量的属性。以下是使用更大对象的示例：
let earth = {
continents: {
australia: {
geography: {}
}
}
};
let geo = earth.continents.australia.geography;
geo.ocean = "Pacific";
geo.river = "Murray";
geo.mountain = "Kosciuszko";
试试看
更多信息：
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/with
https://yuiblog.com/blog/2006/04/11/with-statement-considered-harmful/