angular - 使用 [...parent.path !] 意味着什么。这？

Question

我检查了 Angular 形式模块，我看到了一个我不认识的语法 [...parent.path !, name];

是 typescript 语法吗？

它可以在 this link 找到这是 Angular github 代码。

Answer 1

如指示 here .

A new ! post-fix expression operator may be used to assert that its operand is non-null and non-undefined in contexts where the type checker is unable to conclude that fact. Specifically, the operation x! produces a value of the type of x with null and undefined excluded. Similar to type assertions of the forms <T>x and x as T, the ! non-null assertion operator is simply removed in the emitted JavaScript code.

// Compiled with --strictNullChecks
function validateEntity(e?: Entity) {
    // Throw exception if e is null or invalid entity
}

function processEntity(e?: Entity) {
    validateEntity(e);
    let s = e!.name;  // Assert that e is non-null and access name
}

表示非空值。