【快应用】如何获取异步回调方法中返回的值
背景：异步回调或者异步promise的方式调用给参数deviceInfo赋值，然后再通过console日志输出，打印的参数的值为空，该如何处理？
相关代码：
<script>
import push from "@service.push";
import device from '@system.device';
const injectRef = Object.getPrototypeOf(global) || global;
// injection regeneratorRuntime
injectRef.regeneratorRuntime = require('@babel/runtime/regenerator');
module.exports = {
data: {
deviceInfo: ''
},
onCreate() {
this.testAsync();
console.log("this.$def.data：", this.$def.data);
},
async testAsync() {
try {
let res = await device.getInfo();
console.info("get device id " + JSON.stringify(res.data));
this.$def.data.deviceInfo = res.data
} catch (e) {
console.log("get device id error " + e.code);
}
},
onDestroy() {
console.info("Application onDestroy");
},
dataApp: {
localeData: {}
}
};
</script>
运行效果：
原因及解决方案:
异步方法的回调方法是异步返回的，调用该方法后，立刻打印该方法中的值，此时异步方法还未执行完成，就会导致后面打印的值为空。可以加50ms的延时待异步方法返回结果后再去执行后面的代码。
示例代码：
<script>
import push from "@service.push";
import device from '@system.device';
const injectRef = Object.getPrototypeOf(global) || global;
// injection regeneratorRuntime
injectRef.regeneratorRuntime = require('@babel/runtime/regenerator');
module.exports = {
data: {
deviceInfo: ''
},
onCreate() {
this.testAsync();
setTimeout(() => {
console.log("this.$def.data：", this.$def.data);
}, 50);
},
async testAsync() {
try {
let res = await device.getInfo();
console.info("get device id " + JSON.stringify(res.data));
this.$def.data.deviceInfo = res.data
} catch (e) {
console.log("get device id error " + e.code);
}
},
onDestroy() {
console.info("Application onDestroy");
},
dataApp: {
localeData: {}
}
};
</script>运行效果：
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