Javascript syntax error on Internet Explorer

Question

I have the following bit of code which adjusts the headers of some parsed data:

    var parsedData = transposed.map(row =>
        row.reduce((acc, col, ind) => {
            acc[headers[ind]] = col;
            return acc;
        }, { }));

The code works fine on Chrome/Edge/Firefox but fails on Internet Explorer saying there's a syntax error at: row =>.

I'm unable to determine where the syntax error is being thrown - I'm relatively new to javascript's map function so I may be missing something. Where in the above code snippet is the syntax error?

user3536179 · Accepted Answer · 2017-02-07 01:27:09Z

10

Arrow functions are a core part of the ES6 language feature set.

Those are not directly supported in IE, you need to transpile your code first.

Babel is the go-to transpiler for ES6.

answered Feb 7, 2017 at 1:27

user3536179

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nzjun90 · Accepted Answer · 2017-02-07 01:28:54Z

3

IE is old and does not understand the arrow function syntax.

reference: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Functions/Arrow_functions

you might need to use the old anonymous function to make it compatible with IE ~~or if polyfill exists, use those.~~ or use transpilers (such as Babel) to transpile it to es5.

example of old annonymous function:

transposed.map(function(row){
        row.reduce((acc, col, ind) => {
            acc[headers[ind]] = col;
            return acc;
   }, { });
});

but remember, you will lose scope of the outside this

edited Feb 7, 2017 at 1:28

answered Feb 7, 2017 at 1:22

nzjun90

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1 Comment

Amadan Over a year ago

Also, there's two arrow functions in OP's example, you only translated the outer one :)

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