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JavaScript - foreach array of arrays
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In this article, we would like to show you how to use a nested for-each loop to iterate an array of arrays in JavaScript.
This section shows how to use forEach method to iterate over an array of arrays.
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let array = [['item 1', 'item 2'],['item 3', 'item 4']];2
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array.forEach((child) => {4
child.forEach((item, index) => {5
console.log('child index ' + index + ': ' + item);6
})7
});Note:
Array.prototype.forEachmethod was introduced in ES5 (ECMAScript 2009).
This section shows how to use for-of loop construction to iterate over an array of arrays.
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let array = [['item 1', 'item 2'],['item 3', 'item 4']];2
3
for(let child of array) {4
for(let item of child){5
console.log(item);6
}7
}Note:
for-ofloop was introduced in ES6 (ECMAScript 2015).
This section shows how to use for-in loop construction to iterate over an array of arrays.
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let array = [['item 1', 'item 2'],['item 3', 'item 4']];2
3
for(var key1 in array) {4
if(array.hasOwnProperty(key1)) {5
let child = array[key1];6
for(var key2 in child) {7
if(child.hasOwnProperty(key2)) {8
console.log(child[key2]);9
}10
}11
}12
}Note: using
for-inloop with array is risky because of possible additional array properties -array.hasOwnProperty(key)method solves the problem.
