重复的字符串值需要分开

let s = 'abcabc'
console.log(s.slice(0, s.length/2));

var string = 'ababab',
    array = string.split(/(.+?)(?=\1)/).filter(Boolean);
    
console.log(array)

function inHalf(str) {
  let middle = Math.ceil(str.length / 2);
  return str.slice(0, middle);
}

console.log(inHalf("abcabc"))
console.log(inHalf("bacbac"))
console.log(inHalf("somethingsomething"))

var string = "Hello abcabc world defgdefg blah blah";
console.log(string.replace(/\b(.*)\1\b/mg, "$1"));