destructuring assignment on array `process.argv` return Cannot read property 'next on nodejs

Asked Dec 06 '16 at 14:08

Active Dec 06 '16 at 14:27

Viewed 586 times

I am using nodejs when using destructuring assignment on array process.argv I get error Cannot read property 'next' of undefined.

How to fix this issue? Why is that? Notes: I am using node v6.9.1

let fileIn, fileOut;
let getNodeArguments = () => {
    // this is ok
    process.argv.forEach((val, index) => {
         console.log(`${index}: ${val}`);
    });
    // this is ok
    var hasFileInOutArgs = process.argv.length === 4;
    if (!hasFileInOutArgs) {
        throw ('arguments for file-in and file-out must be provided');
    }
    // issue
    var [, , argUrlIn, argUrlOut] = process.argv;  // error exception here <<<
    fileIn = argUrlIn;
    fileOut = argUrlOut;
};
getNodeArguments();

More infos:

https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Nested_object_and_array_destructuring

edited Dec 06 '16 at 14:27

asked Dec 06 '16 at 14:08

Radex

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I would like to create two variable argUrlIn and argUrlIn which are populate with value from process.argv process[2] and process[3] – Radex Dec 06 '16 at 14:13
what is your node version? – ltamajs Dec 06 '16 at 14:14
1

I am using v6.9.1 – Radex Dec 06 '16 at 14:16
could be related http://stackoverflow.com/questions/17379277/destructuring-in-node-js – Radex Dec 06 '16 at 14:19
1

Your code works fine in Node 6.2.2. – Pointy Dec 06 '16 at 14:24
I cannot reproduce that in Node v6.9.1. – Michał Perłakowski Dec 06 '16 at 14:25
how do you know it breaks there? the problem is in next() which is nowhere in the code you shown? – Lyubomir Dec 06 '16 at 14:26
Thanks guys for your hint, I have notice that code run fine when I run in node directly, but I get an error when debugging it using latest version of visual studio code. Do you know how could fix this issue on VSCODE? – Radex Dec 06 '16 at 14:35
It is always as simple as `var [, , argUrlIn, argUrlOut] = process.argv || [];`, Don't forget to assign default values if they aren't supposed to be undefined. – Estus Flask Dec 06 '16 at 14:41

destructuring assignment on array `process.argv` return Cannot read property 'next on nodejs

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