What happens when the delete operator cannot be used in js? How to deal with it

What this article brings to you is about the situation where the delete operator cannot be used in js. The processing method has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

delete is a unary operator, used to delete attributes or array elements of an object. Return true or false.

Situations that cannot be deleted:

1. Use variables defined by var.

2. Built-in object properties (not configurable).

3. The function and parameters defined by the function statement.

In strict mode, deleting a non-configurable attribute will report a type error. In non-strict mode, using the delete operation returns false.

In strict mode, the specified object and its attributes must be displayed when using delete, otherwise a syntax error will be reported.

For example:

var name = "a";
window.age = 10;
delete window.name;//IE<9时报错，其他浏览器返回false
delete window.age;//IE<9时报错，其他浏览器返回true

The reason why variables declared using var cannot be deleted: The window attribute added using the var statement has a feature called configurable, and its value is set to false.

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