Vue3的watchEffect的使用
# Vue3的watchEffect的使用
- 它会监听所有的响应式数据,并且会立即执行,类似于Vue2中的watch的配置 immediate
- 它有两个API
- stop :停止侦听
- onInvalidate :清除副作用的函数
- flush(3个参数) : pre(默认) post(Dom挂载后执行) sync(不推荐使用 强制同步)
# stop的使用 示例
<template>
<div>
{{ num }}
{{ content }}
<button @click="changeNum">点击</button>
</div>
</template>
<script>
import { ref, watchEffect } from "vue";
export default {
setup(props, { attrs, slots, emit }) {
let num = ref("1");
let content = ref(0);
const changeNum = () => {
content.value++;
num.value = "2";
if (content.value == 10) {
stop();
}
};
const stop = watchEffect(() => {
console.log(content.value);
});
return {
num,
changeNum,
content,
};
},
};
</script>
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# onInvalidate的使用 示例
<template>
<div>
{{ num }}
{{ content }}
<button @click="changeNum">点击</button>
</div>
</template>
<script>
import { ref, watchEffect } from "vue";
export default {
setup(props, { attrs, slots, emit }) {
let num = ref("1");
let content = ref(0);
const changeNum = () => {
content.value++;
num.value = "2";
};
const stop = watchEffect((onInvalidate) => {
console.log(content.value);
let time = setTimeout(() => {
console.log("发送请求成功~");
}, 2000);
onInvalidate(() => {
clearTimeout(time);
});
});
return {
num,
changeNum,
content,
};
},
};
</script>
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# flush的使用
<template>
<div>
<div ref="Dom">我是Dom</div>
</div>
</template>
<script>
import { ref, watchEffect } from "vue";
export default {
setup(props, { attrs, slots, emit }) {
const Dom = ref(null);
const stop = watchEffect(
() => {
console.log(Dom.value);
},
{
flush: "post",
}
);
return {
Dom,
};
},
};
</script>
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