typescript indexOf报错“类型“string”的参数不能赋给类型“never”的参数”

Question

const formState = reactive({
   associTag:"",
   dynamicTags:[]
})

function confirmAdd(){
    if(formState.dynamicTags.length==0 || formState.dynamicTags.indexOf(formState.associTag)==-1){
        formState.dynamicTags.push(formState.associTag);
    }
}

刚学习ts，报错确实让人很头疼

Answer 1

dynamicTags 没定义类型，默认是 Array<never>。

假设你里面要放的元素是类型 Foo，那么声明时需要：

{
    dynamicTags: [] as Foo[],
    dynamicTags: [] as Array<Foo>,
    dynamicTags: new Array<Foo>()
}

几种写法都可以，推荐第一种。