let data = ['apple', 'banana', 'orange']
 
data.map((item,index) => {
   if(index == 2){
      data.unshift(data.splice(index , 1)[0]);
   }
})
console.log(data) // ['orange', 'apple', 'banana']

其他方法：

for (var i = 0; i < arr.length; i++) {
    if (arr[i] === key) {
	    arr.splice(i, 1);
	    break;
    }
}
arr.unshift(key);

如果是数组对象的话：

let  arr = [{name:'章三',age:1},{name:'li',age:2},{name:'wang',age:4},{name:'liu',age:9}]
let obj = {};
arr.forEach((item,index)=>{
    if(item.name === 'li'){
        obj = item;
        arr.splice(index,1)
        return;
    }
 
})
 
arr.unshift(obj);
console.log(arr);