返回从最终 object 推入对象数组的键

Question

Trying to return the last key from an object pushed into an array

var remove = function(s, k) {
   let stack = [];
   let newObj = {}; 
   for(const char of s){
    let letter = stack[stack.length-1]
    console.log(`stack: ${stack[stack.length-1][0]}`)
    if(char !== letter){
        newObj[char] = newObj[char] ? newObj[char]+1 : 1
[Object.values(newObj).length-1])
        stack.push({newObj})
    } 
    else if(char === letter && Object.values(newObj)[Object.values(newObj).length-1]){
        stack.pop()
    }
    }
}

If I pass in

const s = "deeedbbcccbdaa"; 
const k = 3;

I expect my console.logs to retun the last letter I pushed into the array. However this is what I'm seeing currently:

TypeError: Cannot read properties of undefined (reading '0')

Answer 1

Can't we use unshift

let text = "deeedbbcccbdaa";
const myArray = text.split("");

console.log(myArray[myArray.unshift()-1])

Try it

Answer 2

You are getting this error because the before you enter the for loop, you assign stack to an empty array ( let stack = [] ).

This means that on the first iteration of your for loop, you are trying to access the last element of stack in your console.log statement, even though it doesn't exist yet.

In other words, the first time your for loop runs, stack[stack.length-1] is undefined. So the error comes from trying to access index 0 of this value.

Hope that helps!