While-loop with arrays in JavaScript-CodePudding

I need help with this code in Js. this example :

let friends = ["Ahmed", "Sayed", "Ali", 1, 2, "Mahmoud", "Amany"];
let index = 0;
let counter = 0;



// // Output
// "1 => Sayed"
// "2 => Mahmoud"



while(index < friends.length){
    index  ;
    if ( typeof friends[index] === "number"){
        continue;
    }
    if (friends[index][counter] === "A"){
        continue;
    }
    console.log(friends[index]);

}

When I did it the massage appear to me,

seventh_lesson.js:203 Uncaught TypeError: Cannot read properties of undefined (reading '0') at seventh_lesson.js:203.

and then I changed this line

if (friends[index][counter] === "A"){continue;
}

with this

if (friends[index].startsWith("A")){continue;}

and still doesn’t work, I don’t know why?

Is the reason there are numbers in the array?

CodePudding user response：

You should increase the index at the end of the loop, otherwise you skip the first element and overshoot the last one.

while(index < friends.length){
    if ( typeof friends[index] === "number"){
        continue;
    }
    if (friends[index][counter] === "A"){
        continue;
    }
    console.log(friends[index]);
    index  ;
}

A better way to iterate through the array would be a for...of loop, so you won't have to use the index at all.

for(const friend of friends)
    if ( typeof friend === "number"){
        continue;
    }
    if (friend[counter] === "A"){
        continue;
    }
    console.log(friend);
}

CodePudding user response：

Try this code

    let friends = ["Ahmed", "Sayed", "Ali", 1, 2, "Mahmoud", "Amany"];
    let index = -1;
    
    
    
    // // Output
    // "1 => Sayed"
    // "2 => Mahmoud"
    
    while(index < friends.length-1){
        index  ;
         
        if ( typeof friends[index] === "number"){
            continue;
        }
        if (friends[index].charAt(0) === "A"){
            continue;
        }
       
        console.log(friends[index]);
    
    }

OR 

let friends = ["Ahmed", "Sayed", "Ali", 1, 2, "Mahmoud", "Amany"];
friends.filter((o)=>{
  if(typeof(o)!="number"&&!o.startsWith("A"))
  console.log(o)
})