In JavaScript, you can make all strings in an array of strings uppercase by calling the String.prototype.toUpperCase()
method on every element of the array using Array.prototype.map()
, for example, like so:
// ES6+
const arr = ['foo', 'Bar', 'bAz'];
const newArr = arr.map((str) => str.toUpperCase());
console.log(newArr); // ['FOO', 'BAR', 'BAZ']
You can rewrite the callback to Array.prototype.map()
without arrow function to make it compatible with ES5.
The code above would create a new array with all strings in the array in uppercase. You can achieve the same with a simple for
loop as well:
const arr = ['foo', 'Bar', 'bAz'];
const newArr = [];
for (let i = 0; i < arr.length; i++) {
newArr.push(arr[i].toUpperCase());
}
console.log(newArr); // ['FOO', 'BAR', 'BAZ']
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