const orders = [500, 30, 99, 15, 223]; /** * Reduce * @return a single value as output */ const total = orders.reduce((acc, cur) => acc + cur) /** * Map * @return an array as output */ const withTax = orders.map(v => v * 1.1) /** * Filter * @return an array as output */ const highValue = orders.filter(v => v > 100); /** * Every * @return a single boolean output */ const everyValueGreaterThan50 = orders.every(v => v > 50) const everyValueGreaterThan10 = orders.every(v => v > 10) /** * Some * @return a single boolean output */ const someValueGreaterThan500 = orders.some(v => v > 500) /** * Some * @returns true */ const someValueGreaterThan10 = orders.some(v => v > 10) /** * Variable Evaluation * Reference: * https://stackoverflow.com/questions/2647867/how-can-i-determine-if-a-variable-is-undefined-or-null */ if (typeof EmpName != 'undefined' && EmpName) { /* will evaluate to true if value is not: null undefined NaN empty string ("") 0 false */ /** * Remove duplicate from array * Reference: * https://stackoverflow.com/questions/2647867/how-can-i-determine-if-a-variable-is-undefined-or-null */ //from simple array var arr = [1,2,3,4,5,1,1,2]; const remDuplicateWithSet = (data) => { return [...new Set(data)] } console.log(remDuplicateWithSet(arr)); // from array of objects var arrayObj = [ { 'id':'1', 'name':'iri1', }, { 'id':'2', 'name':'iri2', }, { 'id':'3', 'name':'iri3', }, { 'id':'1', 'name':'iri1', }, { 'id':'3', 'name':'iri1', }, { 'id':'3', 'name':'iri1', }, ]; function removeDuplicates(array, key) { return array.filter((obj, index, self) => index === self.findIndex((el) => ( el[key] === obj[key] )) ) } console.log(removeDuplicates(arrayObj, 'id')) /** * Add and remove elements on arrays */ addAndRemove() { let A = [ { id: 1, }, { id: 2, }, { id: 3, }, ]; const B = [ { id: 1, }, { id: 4, }, { id: 5, }, ]; // add B.forEach((obj) => { if ( !A.find((x) => { return x.id == obj.id; }) ) { A.push(obj); } }); // remove A.forEach((obj, index, array) => { if ( !B.find((x) => { return x.id == obj.id; }) ) { array.splice(index, 1); } }); } /** * Some References: * Array Docs: https://www.tutorialspoint.com/es6/es6_arrays.htm */