Array[i].replace(/城區(qū)/g,"城區(qū)n");
不過我不知道對中文有沒有效果

我這個要把你的可能出現(xiàn)的中隊列出來畢竟中隊好列城區(qū)不好列

var xaxis = ["城區(qū)一中隊","城區(qū)二中隊","城區(qū)三中隊","大溪中隊","澤國中隊","溫嶠中隊","新河中隊","箬橫中隊","城南中隊","濱海中隊","松門中隊","石塘中隊"]
function _replace(arr,rule){
  var reg = null;
  return arr.map(v=>{
    for(var i=0;i<rule.length;i++){
      reg = new RegExp(rule[i]);
      if(reg.test(v)){
        return v.replace(reg,$1=>"\n"+$1);
      }
    }
  })
}
console.log(_replace(xaxis,["一中隊","二中隊","三中隊","中隊"]))

var arr1 = []
xaxis.forEach(function(item){
    if(item.indexOf('城區(qū)')!=-1) {
        arr1.push('城區(qū)\n' + item.substr(2,item.length));
    } else {
        arr1.push(item.substr(0,2) + '\n中隊');
    }
})

xaxis = xaxis.map(e=>e.replace('中隊','\n中隊'))

xaxis = xaxis.map(v => `${v.slice(0,2)}\n${v.slice(2)}`)

3個字開頭就跪了