World Factbook

1) Get a button for each letter

• Show a button for each letter that a country can begin with
• You can use a Set to remove duplicates from a list.

Input

fetch('/worldl.json') .then((r)=>r.json()) .then((r)=>{ let letters = r.map(c=>c.name[0]); for(let a of letters){ let b = document.createElement('button'); b.innerText = a; document.body.append(b); } });

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fetch('/worldl.json')

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  .then((r)=>r.json())

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  .then((r)=>{

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     let letters = r.map(c=>c.name[0]);

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     for(let a of letters){

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       let b = document.createElement('button');

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       b.innerText = a;

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       document.body.append(b);

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     }

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  });

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​

Go reset

Output

fetch('/worldl.json')
  .then((r)=>r.json())
  .then((r)=>{
     let letters = r.map(c=>c.name[0]);
     for(let a of letters){
       let b = document.createElement('button');
       b.innerText = a;
       document.body.append(b);
     }
  });

fetch('/worldl.json')
  .then((r)=>r.json())
  .then((r)=>{
     let letters = new Set(r.map(c=>c.name[0]));
     for(let a of letters){
       let b = document.createElement('button');
       b.innerText = a;
       document.body.append(b);
     }
  });