JSFiddle - React, Tailwind, and code Playground

JavaScript

const arr = ['0.5', 2];
const sumElements = arr => {
  const isString = n => Object.prototype.toString.call(n) === '[object String]';
  const check = n => {
    if (!isFinite(n) && !isString(n)) {
    	console.log('if if');
      return 0;
    } else if (parseFloat(n)) {
    	console.error('float', parseFloat(n))
      return parseFloat(n);
    } else {
    	console.log('if if last');
      return 0;
    }
  };
  return arr.reduce((initial, next) => check(initial) + check(next), 0);
};


console.error('result', sumElements(arr));