How to extract top-left and bottom-right coordinates from bounds value-CodePudding

I am trying to extract the X and Y coordinates of the top-right & bottom-left of a text box given the value of the bound.

Example: [84,672][1356,889]

Is there a quick and easy function available in JavaScript that would extract the above values into two separate variables so that I can then calculate the center coordinates? Like:

A = [84,672]
B = [1356,889]

CodePudding user response：

You can use a RegEx:

const input = "[84,672][1356,889]";

// parse input
const nums = input.match(/\d /g).map(Number);
const A = [nums[0], nums[1]];
const B = [nums[2], nums[3]];

console.log(A, B);

// calculate midpoint
const mdpt = [(A[0] B[0])/2, (A[1] B[1])/2];
console.log(mdpt);

CodePudding user response：

There is no quick and simple single function that will do that, no. But you can use simple string functions to make your own:

Here I used substring, indexOf, replace, and split.

As the result was an array, I used map to convert the original strings to numbers, and destructuring assignment to get the results.

const input = "[84,672][1356,889]";

function extractCoordinates(input) {
  // get a and b as strings using indexOf with offset
  const aStr = input.substring(0, input.indexOf('[', 1));
  const bStr = input.substring(input.indexOf('[', 1), input.length);
  // create a function that will remove the brackets and coerce to a number
  const mapToNumber = (s) =>  s.replace(/\[|\]/g, '');
  // split the strings on the comma and run the function on the parts
  const a = aStr.split(',').map(mapToNumber);
  const b = bStr.split(',').map(mapToNumber);
  // And that's it
  return [a, b];
}

// Here I use array destructuring to get the results:
const [a, b] = extractCoordinates(input);
console.log(a, b);

CodePudding user response：

Another option is to convert your string into a valid JSON string so that:

"[84,672][1356,889]"

becomes

"[[84,672],[1356,889]]"

You can do this by replacing ][ with ], [ and wrapping your string in[]. Then you can parse this string into a JavaScript array, and use indexing to extract the values into variables:

const A = arr[0];
const B = arr[1];

Or you can use destructuring assignment as shown below to extract the nested arrays into variables

const str = "[84,672][1356,889]";
const [A, B] = JSON.parse(`[${str.replaceAll("][", "],[")}]`);

console.log(A);
console.log(B);

Note: If you can't support replaceAll(), you can use a global regular expression with the .replace() method instead: .replace(/]\[/g, '],[')