ES6 的模板字符串为生成字符串提供了很大的灵活性，你可以举个例子吗？ ​

`string text``string text line 1
 string text line 2``string text ${expression} string text`;

tag`string text ${expression} string text`;

console.log(`string text line 1
string text line 2`);
// "string text line 1
// string text line 2"

var a = 5;
var b = 10;
console.log(`Fifteen is ${a + b} and\nnot ${2 * a + b}.`);
// "Fifteen is 15 and
// not 20."

//show函数采用rest参数的写法如下：

let name = "张三",
  age = 20,
  message = show`我来给大家介绍:${name}的年龄是${age}.`;

function show(stringArr, ...values) {
  let output = "";

  let index = 0;

  for (; index < values.length; index++) {
    output += stringArr[index] + values[index];
  }

  output += stringArr[index];

  return output;
}

message; //"我来给大家介绍:张三的年龄是20."