JavaScript is a versatile language that has various features, functionalities, classes, libraries, frameworks, etc. Programmers and developers all over the globe try to get most of the JavaScript programming language. There are many projects that programmers are working on to make web pages, mobile applications, etc. When it is widely used, it is quite normal to encounter errors, and “possible unhandled promise rejection (id:0)” is one of those.
No matter how tough the error looks, you don’t need to worry when you encounter this error as we are here to help you crack the code and explain it to you in a simpler way so that even newbies can understand it. Let’s discuss how the error occurs
How the error warning pops up
When you try to code a program with an empty AsyncStorage item, you end up with an error warning. Check out the code
componentDidMount() {
try {
// This warning only appears when 'connections' item is empty
AsyncStorage.getItem('connections').then((token) => {
token = JSON.parse(token);
const getSectionData = (dataBlob, sectionId) => dataBlob[sectionId];
const getRowData = (dataBlob, sectionId, rowId) => dataBlob[`${rowId}`];
const ds = new ListView.DataSource({
rowHasChanged: (r1, r2) => r1 !== r2,
sectionHeaderHasChanged: (s1, s2) => s1 !== s2,
getSectionData,
getRowData,
});
const {dataBlob, sectionIds, rowIds} = this.formatData(token);
this.setState({
dataSource: ds.cloneWithRowsAndSections(dataBlob, sectionIds, rowIds),
});
});
}catch(error) {
console.log(error);
}
}The Solution to Fix the Error “possible unhandled promise rejection (id:0)”
The error warning appears when ‘await’ is not used in the code. The try and catch do not work if you forgot to add await. In order to solve the error, you need to add the catch block where you are getting the promise error. Have a look at the solution code
componentDidMount() {
// This warning only appears when 'connections' item is empty
return AsyncStorage.getItem('connections').then((token) => {
token = JSON.parse(token);
const getSectionData = (dataBlob, sectionId) => dataBlob[sectionId];
const getRowData = (dataBlob, sectionId, rowId) => dataBlob[`${rowId}`];
const ds = new ListView.DataSource({
rowHasChanged: (r1, r2) => r1 !== r2,
sectionHeaderHasChanged: (s1, s2) => s1 !== s2,
getSectionData,
getRowData,
});
const { dataBlob, sectionIds, rowIds } = this.formatData(token);
this.setState({
dataSource: ds.cloneWithRowsAndSections(dataBlob, sectionIds, rowIds),
});
}).catch(error => {
console.log(error);
})
}Placing the catch block at the right place where you are receiving the promise error can catch the error. This way, you can resolve the error.
Conclusion
And here we are the solution to handle the error warning “possible unhandled promise rejection (id:0)”. With this solution and the tips, you can easily solve the issue. The main point to remember is to use the ‘catch’ block so the error got caught.
I hope you like the solution! I wish you luck! If you need any assistance, don’t forget to drop a message in the below comment box. If you like the post, write back to give you feedback.