Javascript filter map code example

Example 1: use .map(), .filter() js

var arr = [1, 25, 20, 4];

var sum = arr.map((item) => item * 10).filter((item) => item > 100);
var sum2 = arr.map((item) => item * 10)
console.log("sum2", sum2)
// sum2 : (4) [10, 250, 200, 40]
console.log("sum", sum);
// sum : (2) [250, 200]

Example 2: js map filter reduce

const numbers = [1, 2, 3, 4];
const doubled = numbers.map(item => item * 2);
console.log(doubled); // [2, 4, 6, 8]

Example 3: map&filter

const files = [ 'foo.txt ', '.bar', '   ', 'baz.foo' ];
const filePaths = files
  .map(file => file.trim())
  .filter(Boolean)
  .map(fileName => `~/cool_app/${fileName}`);

// filePaths = [ '~/cool_app/foo.txt', '~/cool_app/.bar', '~/cool_app/baz.foo']

Example 4: map&filter

const files = [ 'foo.txt ', '.bar', '   ', 'baz.foo' ];
const filePaths = files.reduce((acc, file) => {
  const fileName = file.trim();
  if(fileName) {
    const filePath = `~/cool_app/${fileName}`;
    acc.push(filePath);
  }
  return acc;
}, []);

// filePaths = [ '~/cool_app/foo.txt', '~/cool_app/.bar', '~/cool_app/baz.foo']