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defineProps
There is no need to introduce it when using it. The default is the global method.
Used in vue3 projects developed by js
const props = defineProps({ attr1: { type: String, // S 必须大写 default: "", }, attr2: Boolean, attr3: { type: Number, required: true, }, });
The usage in js environment is similar to that of vue2, except that the optional API is replaced by Composable API. The defined props type and default value are the same as the vue2 type. The defineProps
API is used in vue3, which will not be introduced here.
Used in the vue3 project developed by ts
interface DeatilInf { aaa: string; bbb: number; } const props = withDefaults( // 参数一:定义props类型:? 代表非必传字段, :号后面紧跟的是数据类型或自定义接口, | 或多种类型 defineProps<{ name: string; age?: number; detail?: DeatilInf | any; }>(), // 参数二:指定非必传字段的默认值 { age: 18, detail: {}, } );
Use typeScript to develop the vue3 project to define props. There are two main APIs used: defineProps
Define the received props, withDefaults
Define the received type.
Of course, you can define props in the same way as a JavaScript environment, but this defeats the point of using TypeScript.
is different from vue2: vue3 needs to define the event before triggering the event. In Vue3, `defineEmits` is also a global API
Used in js
const emits = defineEmits(["change", "input"]); emits("chage", "data"); emits("input", { data: 123 });
Used in TS
enum EventName { CHANGE = "change", INPUT = "input", } const emits = defineEmits<{ (event: EventName.CHANGE, data: string[]): void; (event: EventName.INPUT, data: string): void; }>(); emits(EventName.CHANGE, ["data"]); emits(EventName.INPUT, "123");
The above code uses enumerationenum
to avoid the appearance of "magic strings". It is worth mentioning that js can also be used in ts, so it will not play its role.
Especially in large-scale projects, unexpected errors may occur when triggering data types, so it may take hours to locate the error. The magic string may be written incorrectly, resulting in the failure to achieve the expected event triggering effect.
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