Issue with Vue 3 / Typescript: Unable to locate variable name in template

Question

Issue with Vue 3 / Typescript: Unable to locate variable name in template

When working with Vue 3 and Typescript, I encountered an error that says "Cannot find name" when trying to reference a data variable in a certain area. How can I resolve this issue? Attached is a screenshot for reference: https://i.sstatic.net/1fknF.jpg. Thank you in advance.

typescript vue.js vuejs3

Answer 1

Answer №1

While grappling with a similar issue after inserting lang="ts" into my vue file due to being new to Vue 3 and Typescript, I managed to find a solution through the following steps:

export default

should be changed to

export default defineComponent({

inside your .vue file.

Make sure you include the import statement.

import { defineComponent }

Also remember to place your data within the setup function.

setup () {
  return {
    loader: false,
    error: false,
    firstTime: false

Answer 2

While grappling with a similar issue after inserting lang="ts" into my vue file due to being new to Vue 3 and Typescript, I managed to find a solution through the following steps:

export default

should be changed to

export default defineComponent({

inside your .vue file.

Make sure you include the import statement.

import { defineComponent }

Also remember to place your data within the setup function.

setup () {
  return {
    loader: false,
    error: false,
    firstTime: false

Answer 3

Answer №2

Encountering the same bug of code inference error due to a loop reference in my code.

I defined a route array constant in route.ts, like this:

import { RouteRecordRaw, createRouter, createWebHistory } from "vue-router";

import Layout from "../layout/index";

export const NaviHeaderRoutes: RouteRecordRaw[] = [
  {
    path: "/foo",
  // Remaining code omitted for brevity...
];

const routes: RouteRecordRaw[] = [
  ...NaviHeaderRoutes
];

const router = createRouter({
  history: createWebHistory(),
  routes
});

export default router;

Then I used NaviHeaderRoutes in the child component of Layout.vue

// layout.vue
// Remaining code omitted for brevity...
<sciprt lang="ts" setup>
//Remaining code omitted for brevity...
</script>

// naviheader
// Remaining code omitted for brevity...
<script lang="ts" setup>
import {NaviHeaderRoutes} from '@/router'
//Remaining code omitted for brevity...
</script>

The fix is simple, just ensure to set the route's component later in your code.

export const NaviHeaderRoutes: RouteRecordRaw[] = [
  {
    path: "/foo",
    name: "FOO",
    redirect: "/foo/index",
    // component: Layout,
// ....
]

const routes: RouteRecordRaw[] = [
  ...NaviHeaderRoutes.map((x) => {
    x.component = Layout;
    return x;
  })
];

Answer 4

Encountering the same bug of code inference error due to a loop reference in my code.

I defined a route array constant in route.ts, like this:

import { RouteRecordRaw, createRouter, createWebHistory } from "vue-router";

import Layout from "../layout/index";

export const NaviHeaderRoutes: RouteRecordRaw[] = [
  {
    path: "/foo",
  // Remaining code omitted for brevity...
];

const routes: RouteRecordRaw[] = [
  ...NaviHeaderRoutes
];

const router = createRouter({
  history: createWebHistory(),
  routes
});

export default router;

Then I used NaviHeaderRoutes in the child component of Layout.vue

// layout.vue
// Remaining code omitted for brevity...
<sciprt lang="ts" setup>
//Remaining code omitted for brevity...
</script>

// naviheader
// Remaining code omitted for brevity...
<script lang="ts" setup>
import {NaviHeaderRoutes} from '@/router'
//Remaining code omitted for brevity...
</script>

The fix is simple, just ensure to set the route's component later in your code.

export const NaviHeaderRoutes: RouteRecordRaw[] = [
  {
    path: "/foo",
    name: "FOO",
    redirect: "/foo/index",
    // component: Layout,
// ....
]

const routes: RouteRecordRaw[] = [
  ...NaviHeaderRoutes.map((x) => {
    x.component = Layout;
    return x;
  })
];

Answer 5

Answer №3

The use of the Composition API offers a significant advantage in addressing this particular issue, as opposed to the Options API which lacks a straightforward solution.

If you are utilizing the Options API and need to tackle this problem, one approach is to create a MyComponent.d.ts file that corresponds with your component and include the following code within it:

declare module '@vue/runtime-core' {
  interface ComponentCustomProperties {
    myTroublesomeVariable: boolean // make adjustments here
  }
}

Answer 6

The use of the Composition API offers a significant advantage in addressing this particular issue, as opposed to the Options API which lacks a straightforward solution.

If you are utilizing the Options API and need to tackle this problem, one approach is to create a MyComponent.d.ts file that corresponds with your component and include the following code within it:

declare module '@vue/runtime-core' {
  interface ComponentCustomProperties {
    myTroublesomeVariable: boolean // make adjustments here
  }
}

Answer 7

Answer №4

I encountered the same issue as well.

Despite checking through VSCode/TS and Volar, I couldn't pinpoint a solution.

To demonstrate the problem, I created a small example (intended to share on Discord):

<template>
  <input v-model="email" />
</template>

<script setup lang="ts">
  import { ref } from 'vue'

  const email = ref('')
</script>

Interestingly, saving this file as Test.vue seemed to resolve the error in other files. Unfortunately, I'm unsure of the exact reason behind it...

Answer 8

I encountered the same issue as well.

Despite checking through VSCode/TS and Volar, I couldn't pinpoint a solution.

To demonstrate the problem, I created a small example (intended to share on Discord):

<template>
  <input v-model="email" />
</template>

<script setup lang="ts">
  import { ref } from 'vue'

  const email = ref('')
</script>

Interestingly, saving this file as Test.vue seemed to resolve the error in other files. Unfortunately, I'm unsure of the exact reason behind it...

Answer 9

Answer №5

Although it's unclear if you're currently experiencing this issue, I once encountered a similar bug that I managed to resolve by addressing a subtle TypeScript error. Once I corrected the bug, everything started working smoothly again.

UPDATE: Upon further investigation, I pinpointed the root cause of the bug. Turns out, I mistakenly placed an enum in a *.d.ts file and referenced it in a different file, resulting in the same error you're facing. The lesson learned here is that enums should not be included in *.d.ts files as they are not compiled into JavaScript and lose their values. After rectifying this mistake, the errors ceased to appear. This experience taught me that sometimes, hidden bugs can manifest and trigger these kinds of errors without warning!

Answer 10

Although it's unclear if you're currently experiencing this issue, I once encountered a similar bug that I managed to resolve by addressing a subtle TypeScript error. Once I corrected the bug, everything started working smoothly again.

UPDATE: Upon further investigation, I pinpointed the root cause of the bug. Turns out, I mistakenly placed an enum in a *.d.ts file and referenced it in a different file, resulting in the same error you're facing. The lesson learned here is that enums should not be included in *.d.ts files as they are not compiled into JavaScript and lose their values. After rectifying this mistake, the errors ceased to appear. This experience taught me that sometimes, hidden bugs can manifest and trigger these kinds of errors without warning!

Answer 11

Answer №6

It is recommended to use defineComponent rather than

export default class ParentSupervise extends Vue

. Here is an example:

<template>
  <div class="hello">
    <h1>{{ book.title }}</h1>
  </div>
</template>

<script lang="ts">
import { reactive, ref, defineComponent } from "vue";

interface Book {
  title: string;
}
const HelloWorld = defineComponent({
  data() {
    return {
      boardFields: "燕儿",
    };
  },
  setup() {
    let name = ref("燕");
    const book = reactive({ title: "Vue 3 Guide" }) as Book;
    debugger;
    console.log("name :>> ", name);
    console.log("book :>> ", book);
    // Expose to template
    return {
      book,
      name,
    };
  },
});
export default HelloWorld;
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped lang="scss"></style>

Answer 12

It is recommended to use defineComponent rather than

export default class ParentSupervise extends Vue

. Here is an example:

<template>
  <div class="hello">
    <h1>{{ book.title }}</h1>
  </div>
</template>

<script lang="ts">
import { reactive, ref, defineComponent } from "vue";

interface Book {
  title: string;
}
const HelloWorld = defineComponent({
  data() {
    return {
      boardFields: "燕儿",
    };
  },
  setup() {
    let name = ref("燕");
    const book = reactive({ title: "Vue 3 Guide" }) as Book;
    debugger;
    console.log("name :>> ", name);
    console.log("book :>> ", book);
    // Expose to template
    return {
      book,
      name,
    };
  },
});
export default HelloWorld;
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped lang="scss"></style>

Answer 13

Answer №7

Make sure to include the setup keyword within the

<script lang="ts">

tag like this:

<script setup lang="ts">

Referencing the documentation:

Using <script setup>, any top-level bindings declared inside are accessible directly in the template (...)

More info here

Answer 14

Make sure to include the setup keyword within the

<script lang="ts">

tag like this:

<script setup lang="ts">

Referencing the documentation:

Using <script setup>, any top-level bindings declared inside are accessible directly in the template (...)

More info here

Issue with Vue 3 / Typescript: Unable to locate variable name in template

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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