Disallow Null Comparisons (no-eq-null)

禁止与 null 进行比较 (no-eq-null)

Comparing to null without a type-checking operator (== or !=), can have unintended results as the comparison will evaluate to true when comparing to not just a null, but also an undefined value.

与 null 进行比较时不使用类型检测操作符（== 或 !=），可能得意想不到的的结果，因为 null 其本身以及 null 与 undefined 比较结果都为 true。

if (foo == null) {
  bar();
}

Rule Details

The no-eq-null rule aims reduce potential bug and unwanted behavior by ensuring that comparisons to null only match null, and not also undefined. As such it will flag comparisons to null when using == and !=.

该规则旨在通过确保与 null 比较时只等于 null，而不同时等于 undefined， 来减少潜在的 bug 和 意外行为。因此，它也将标记使用 == 和 != 与 null比较的情况。

Examples of incorrect code for this rule:

错误 代码示例：

/*eslint no-eq-null: "error"*/

if (foo == null) {
  bar();
}

while (qux != null) {
  baz();
}

Examples of correct code for this rule:

正确 代码示例：

/*eslint no-eq-null: "error"*/

if (foo === null) {
  bar();
}

while (qux !== null) {
  baz();
}

Version

This rule was introduced in ESLint 0.0.9.

该规则在 ESLint 0.0.9 中被引入。

Resources

• Rule source
• Documentation source