ReferenceError: variable is not defined after if statement

Question

I'm using an if statement to set page as follows:

 loadMaintenances (query = {}, status) {
             if(status === 'changed'){
                let page = 1
             }
             else{
                let page = this.page
             }

             console.log(page);
}

However, with the above code I'm getting the error;

[Vue warn]: Error in mounted hook: "ReferenceError: page is not defined"

But when I remove it outside of the if statement as follows:

   loadMaintenances (query = {}, status) {
              let page = this.page
             console.log(page);
}

It works. Is something wrong with my if statement?

Amaarockz · Accepted Answer · 2021-01-24 15:36:56Z

5

This is indeed a kings territory problem, each data identifier has its own scope rules and in general 'let' has block scope so the variable that you define using 'let' inside a block is local only inside the block therefore when you try to print it outside it shows as undefined.

A simple solution for this would be declaring the variable page outside the if-block

loadMaintenances (query = {}, status) {
             let page;
             if(status === 'changed'){
                page = 1
             }
             else{
                page = this.page
             }

             console.log(page);
}

answered Jan 24, 2021 at 15:36

Amaarockz

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