vuldin/README.md

## README.md

      
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              README.md
            
          
    This module exports an add closure that takes any number of arguments and/or parameters
Examples:
add()
add(1)
add(1,2)
add(1)(2)
add(1,2)(3,4)

Each given number is added together and the result is returned.
The trick is the use of Symbol.toPrimitive, which allows the returned function to be turned into a number.
Wrap the function call in Number() to print the resulting number. Example: Number(add(1)(2,3)(4)(-100)(123))
This stack overflow comment was helpful in showing how to spread arguments inside function and suggesting to bind 0 to the function instead of handling value inside function
https://stackoverflow.com/a/34776276/2316606

  
## add.js
module.exports = function add() {
  // 'use strict' is needed so this in the add function doesn't refer to global environment
  'use strict'

  // an array of all args plus value of this is reduced to a single value
  const sum = [this, ...arguments].reduce((prev, curr) => prev + curr)

  // bind this value to the function and save into new result object
  const result = add.bind(sum)

  // define the toPrimitive symbol function to return the sum
  result[Symbol.toPrimitive] = () => sum

  return result
}.bind(0)
	module.exports = function add() {
	// 'use strict' is needed so this in the add function doesn't refer to global environment
	'use strict'

	// an array of all args plus value of this is reduced to a single value
	const sum = [this, ...arguments].reduce((prev, curr) => prev + curr)

	// bind this value to the function and save into new result object
	const result = add.bind(sum)

	// define the toPrimitive symbol function to return the sum
	result[Symbol.toPrimitive] = () => sum

	return result
	}.bind(0)