How to escape try/catch hell in JavaScript ?
Last Updated :
15 Jun, 2022
In this article, we will try to understand how we may escape from multiple try/catch hell (that is multiple sequences of occurrences of try/catch blocks) in JavaScript.
Let us first quickly visualize how we may create a try/catch block in JavaScript using the following illustrated syntax:
Syntax: Following is the simple syntax that we may use to create a particular simple try/catch block inside any function or a method:
try {
// do something...
}
catch(errorMessage){
// do something...
}Now, let us see the following syntax which describes how we may have try/catch hell (means multiple try/catch blocks for accessing multiple values):
Syntax:
try {
// do something...
}
catch(error){
// do something...
}
try {
// do something...
}
catch(error){
// do something...
}
...Let us have a look over the below-mentioned example which will help us to understand the above-mentioned syntax of try/catch and also will try to see what is try/catch blocks hell syntax which is described above as a syntax.
Example 1: In this example, we will try to understand the syntax of try/catch block and will further see how we may create a try/catch blocks hell (that is multiple sequences of try/catch blocks hell).
JavaScript
<script>
function nameOfEmployee() {
let name_of_person = new Promise((resolve, reject) => {
setTimeout(() => {
resolve("Johnson...");
}, 1000);
});
return name_of_person;
}
function nameOfOrganization() {
let name_of_organization =
new Promise((resolve, reject) => {
setTimeout(() => {
resolve("GeeksforGeeks...");
}, 2000);
});
return name_of_organization;
}
async function displayData() {
// Here comes the try/catch blocks hell...
// First try/catch block...
try {
let name = await nameOfEmployee();
console.log("Name of an employee is: " + name);
} catch (error) {
console.log(error);
}
// Second try/catch block...
try {
let organization = await nameOfOrganization();
console.log("Name of an organization is: "
+ organization);
} catch (err) {
console.log(err);
}
// As per need more number of try/catch
// blocks may be added...
}
displayData();
</script>
Output:
Name of an employee is: Johnson...
Name of an organization is: GeeksforGeeks...
As we have seen in the above-mentioned example, the try/catch hell for just achieving multiple values in different functions that we have created multiple try/catch blocks which actually becomes a hell. Let us now see how we may avoid unnecessary try/catch block sequences using the below-illustrated example.
Example 2: This example is the extension of the previous example, where we have seen how we may create a try/catch hell and in this, we will avoid using multiple unnecessary try/catch blocks.
JavaScript
<script>
function nameOfEmployee() {
let name_of_person =
new Promise((resolve, reject) => {
setTimeout(() => {
resolve("Johnson...");
}, 1000);
});
return name_of_person;
}
function nameOfOrganization() {
let name_of_organization =
new Promise((resolve, reject) => {
setTimeout(() => {
resolve("GeeksforGeeks...");
}, 2000);
});
return name_of_organization;
}
async function displayData() {
let name = await nameOfEmployee()
.catch((error) => console.log(error));
let organization = await nameOfOrganization()
.catch((error) => console.log(error));
console.log("Name of an employee is: " + name);
console.log("Name of an employee is: " + organization);
}
displayData();
</script>
Output:
Name of an employee is: Johnson...
Name of an organization is: GeeksforGeeks...
The above-illustrated example would be the best approach to avoid multiple try/catch blocks hell, but still, it's getting repetitive. So there is another approach (in the form of an example illustrated below) in which we will create a function or method that is completely responsible for handling all the errors.
Example 3: In this example, we will create a standardized function or a method that will be used to handle all the errors and results which is coming to it in the form of a promise. This example will illustrate the avoidance of try/catch hell (that is usage of multiple try-catch blocks for just fetching different information in several different functions).
JavaScript
<script>
function nameOfEmployee() {
let name_of_person =
new Promise((resolve, reject) => {
setTimeout(() => {
resolve("Johnson...");
}, 1000);
});
return name_of_person;
}
function nameOfOrganization() {
let name_of_organization =
new Promise((resolve, reject) => {
setTimeout(() => {
resolve("GeeksforGeeks...");
}, 2000);
});
return name_of_organization;
}
async function errorHandler(promise) {
try {
let data = await promise();
return [data, null];
} catch (error) {
return [null, error];
}
}
async function displayData() {
let [name, nameError] = await
errorHandler(nameOfEmployee);
let [organization, organizationError]
= await errorHandler(nameOfOrganization);
if (nameError) {
console.log(nameError);
} else {
console.log("Name of an employee is: " + name);
}
if (organizationError) {
console.log(organizationError);
} else {
console.log("Name of an organization is: "
+ organization);
}
}
displayData();
</script>
Output:
Name of an employee is: Johnson...
Name of an organization is: GeeksforGeeks...
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