Return the biggest number in the array (array contains a string)?

Question

I dont understand why my code is not working, when I read it logically I feel that it should work, but what it does is return 3,4,2 as opposed to the highest number of the 3 (i.e. 4)

const array2 = ['a', 3, 4, 2] // should return 4
for(items of array2){
 if(items > 0) {
 console.log(Math.max(items));
}

What am I doing wrong? What have I misinterpreted? Please don't give me the answer, just tell me why my logic does'nt work

• jarmod: Log the value of items. That should hopefully cause you to rename it from items (because it's a single value, not multiple values).
• A_A: Try to print console.log(items, Math.max(items)); instead, I guess then you'll know why it prints 3, 4 and 2
• A_A: Also, you could learn how to use a debugger and step through the code. This will help you in this case, and in many others too

Answer 1

in for-loop, items is just one item actually. Each time, you print the current item. it is basically the same thing with this

const array2 = ['a', 3, 4, 2] // should return 4
for(items of array2){
 if (items > 0) {
 console.log(items);
 }
}

you can do it with this only

const array2 = ['a', 3, 4, 2] // should return 4
console.log(Math.max(...array2.map(s => +s || Number.MIN_SAFE_INTEGER)));

check out: https://stackoverflow.com/a/44208485/16806649

if it was integer-only array, this would be enough:

const array2 = [3, 4, 2] // should return 4
console.log(Math.max(...array2));

• A_A: array2.filter seems more accurate for cases like ['a', -1, -2]
• codemode: makes sense. thanks. updated with Number.MIN_SAFE_INTEGER :)
• Andy: I would avoid calling it items (plural) - it should probably be item (singular), and properly declared with const (in this case).
• codemode: @Andy agree. to show the confusion, I made minimal changes in the original code.

Answer 2

• You just need to filter the array.
• Below example I am using filter() method of array and then just pass that filteredarray to Math.max() function.
• isNan() function returns false for valid number.
• Math.max(...filteredArr) is using spred operator to pass the values.

const arr = ['a', 3, 4, 2];
const filteredArr = arr.filter(val => {
 if (!isNaN(val)) return val;
})
console.log(Math.max(...filteredArr));

• jarmod: Or just: const filteredArr = arr.filter((val) => !isNaN(val));

Answer 3

I don't think you need the "For(items of arr)" instead just if the length of the array is greater than 0, then console.log(Math.max(...arr) should work.

See document ion below:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/max

• Community: Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Answer 4

It is returning 3,4,2 because you are taking array2, and iterating through with each individual element of the array. items is not the entire array, it is the individual element and that is why Math.max of an individual element is just getting the same value.

Answer 5

just you need fliter you're array then get max value, also in arrayFilters function use to removes everything only return numbers of this array

 function arrayFilters(array){
const number = array.filter(element => typeof element === 'number')
 return number;
}
function getMaxValue(number){
 return Math.max.apply(null,number)
}
const arr = ['a',2,3,4];
console.log(getMaxValue(arrayFilters(arr)))