How to throw error before catch block on if condition

Álvaro 0
Viewed 25

I am making a request to an API that gives me some basic account details.

If anything fails connecting to the endpoint, the try catch works correctly and it executes the catch block.

But I want to throw an error depending on the data I am getting, but it defaults to the catch block. How can I do this?

Here is a mockup of what I am trying to achieve.

import axios from 'axios'

export default async () => {
  try {
    const { data } = await axios('https://api.endpoint.com')
    
    if (data.credits < 10) {
      throw 'No enough credits'
    } else {
      return 'All good'
    }

  } catch (error) {
    throw 'Error connecting...'
  }
}
try-catch node.js javascript
3 Answers

Try this

import axios from 'axios'

export default async() => {
  try {
    const { data } = await axios('https://api.endpoint.com')

    if (data.credits < 10) {
      // !important! throw a string, not a new Error
      // since axios won't throw a string
      throw 'No enough credits'; 
    } else {
      return 'All good'
    }

  } catch (error) {
    if (typeof error === "string") throw error;
    throw 'Error connecting...'
  }
}
Jaromanda X0

You are not doing anything with the caught error, if you want to handle the error in the catch block, don't throw a new error.

This code will always throw catch

try {
  throw "not enough credits";
} catch (e) {
  throw "catch";
}

Instead you could for example handle it.

try {
  throw "not enough credits";
} catch (e) {
  console.log(e); // handle the error in some way
}

Rethrowing the caught error just does the same thing as throwing in the first place.

try {
  throw "not enough credits";
} catch (e) {
  throw e;
}

So is basically the same thing as doing this.

throw "not enough credits";

You could throw a new error with some extra data from the caught error.

try {
  throw "not enough credits";
} catch (e) {
  throw `something went wrong: ${e}`;
}

So in your example, you could do something like this.

import axios from 'axios'

export default async () => {
  try {
    const { data } = await axios('https://api.endpoint.com')
    
    if (data.credits < 10) {
      throw 'not enough credits'
    } else {
      return 'All good'
    }

  } catch (error) {
    throw `Error connecting... ${error}`
  }
}

But I would prefer doing something like this.

const getData = () => {
  const data = { credits: 5 };

  if (data.credits < 10) {
    throw 'not enough credits'
  } else {
    return 'All good'
  }
}


// call the function and handle the error on another level
try {
  const data = getData();
  // do something with data
} catch (e) {
  console.log(`fetching data failed: ${e}`);
}

axtck0

Axios already throws error with informative message, so you can throw Error instead of string, and it will look like this:

import axios from 'axios'

export default async () => {
  try {
    const { data } = await axios('https://api.endpoint.com')
    if (data.credits < 10) throw new Error('not enough credits');
    return 'all good' // i think you must return data here btw

  } catch (error) {
    // some logic here if you want...
    // may be console.error(error.message)
    throw error
  }
}
NekkiNekkiNekki0
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