# .cadoles-slide-title[Tableaux (2/2)]
**Méthodes de parcours et transformations**
```js
var arr = [1, 2, 3];

// Traverser le tableau
arr.forEach(function(item, index) {
  console.log('Item:', item, 'Index:', index);
});

// Transformer un tableau
var square = arr.map(function(item, index) {
  return item*item;
}); // -> [1, 4, 9]

// Réduire un tableau
var sum = arr.reduce(function(memo, item, index) {
  return memo+item;
}, 0); // -> 6
```
**Exercice**
```js
var arr = [15, 20, 15, 16, -1, 4];

var max = arr.??(function(??) {
  ??
}, ??);

console.log(max);   // -> 20
```
???

Solution Exo
```js
var arr = [15, 20, 15, 16, -1, 4];

var max = arr.reduce(function(memo, item, index) {
  if(!memo) {
    memo = item;
  } else if(item >= memo) {
    memo = item;
  }
  return memo;
});
```