loop through an array of arrays javascript code example
Example 1: javascript loop through array
var data = [1, 2, 3, 4, 5, 6];
// traditional for loop
for(let i=0; i<=data.length; i++) {
console.log(data[i]) // 1 2 3 4 5 6
}
// using for...of
for(let i of data) {
console.log(i) // 1 2 3 4 5 6
}
// using for...in
for(let i in data) {
console.log(i) // Prints indices for array elements
console.log(data[i]) // 1 2 3 4 5 6
}
// using forEach
data.forEach((i) => {
console.log(i) // 1 2 3 4 5 6
})
// NOTE -> forEach method is about 95% slower than the traditional for loop
// using map
data.map((i) => {
console.log(i) // 1 2 3 4 5 6
})
Example 2: how to cycle through an array js
// Requiring the lodash library
// src: https://lodash.com/docs/4.17.15#forEach
// console: npm i --save lodash
const _ = require("lodash")
// Use of _.forEach() method
_.forEach([1, 2], function(value) {
console.log(value)
});
// => Logs `1` then `2`.
// traversing an object
_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
console.log(key)
})
// => Logs 'a' then 'b' (iteration order is not guaranteed).
//////////////// To not use lodash ////////////////
// src: https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
function logArrayElements(element, index, array) {
console.log("a[" + index + "] = " + element)
}
[2, 5, 9].forEach(logArrayElements)
// logs:
// a[0] = 2
// a[1] = 5
// a[2] = 9