CODEWITHSUNDEEP
javascriptjsonparsingmathmatrix
user3596335
user3596335

Reputation:

Parse array-like string containing variable names to array

I have a default setup where I'm defining a bunch of variables like 

let a="a", b="b", c="c", d="d", ...

and I got a multidimensional array (as string) that is using these variables as values like ...

let matrixString = // (typeof matrixString === "string")
 `[
    [a, b, c, d, a],
    [b, b, c, d, a],
    [c, c, a, a, d]
  ]`

... and I'd like to parse this string using "JSON.parse()" to get a real array from the string but it looks like there is a issue parsing a string with variables inside because I get the error-message 

JSON Parse error: Unexpected identifier "a"

Please have a look at my example:

/* ** default setup ** */
let a="a", b="b", c="c", d="d";
let matrix =  [
  [a, b, c, d, a],
  [b, b, c, d, a],
  [c, c, a, a, d]
]

console.log(matrix)



/* ** here is the issue ** */
let matrixAsString = `[
                        [a, b, c, d, a],
                        [b, b, c, d, a],
                        [c, c, a, a, d]
                      ]`;
try {
  let parsedMatrix = JSON.parse(matrixAsString)
  console.log(parsedMatrix)
} catch(error) {
  // error = 'JSON Parse error: Unexpected identifier "a"'
  console.log(`Error: ${error}`) 
}

How to fix this without using a workaround like mapping the string and adding "" between or using "eval()". Is there a method?

Upvotes: 0

Views: 140

Answers (1)

connexo
connexo

Reputation: 56793

You cannot use JSON.parse() if you don't have JSON to parse in the first place. If you need a more loose definition of JSON to work for you, consider something like https://www.npmjs.com/package/really-relaxed-json.

In this case, though, what you are looking for might be template literals:

/* ** default setup ** */
let a="1", b="2", c="3", d="4";
let matrix =  [
  [a, b, c, d, a],
  [b, b, c, d, a],
  [c, c, a, a, d]
]

console.log(matrix)

let matrixAsTemplateLiteral = `[
                        [${a}, ${b}, ${c}, ${d}, ${a}],
                        [${b}, ${b}, ${c}, ${d}, ${a}],
                        [${c}, ${c}, ${a}, ${a}, ${d}]
                      ]`;
console.log(matrixAsTemplateLiteral);

Upvotes: 1

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