SOURCE

function reverseWord( str ){
    // 首先把字符串拆分成数组
    let strArray = str.split(' ');
    console.log('数组--'+strArray);
    let i = 0, j = strArray.length - 1;
       while(i < j){
        let temp = strArray[i];
        strArray[i] = strArray[j];
        strArray[j] = temp;
        i++;
        j--;
       }
       console.log("交换后的数组"+strArray)
    return strArray.join(' ');
}

let array = reverseWord("It's a Dog!");
document.write("结果"+array);