这样做:

s = 'hello ' + my_name + ', how are you doing'

更新

使用ES6，你也可以这样做:

s = `hello ${my_name}, how are you doing`

试试JS中的sprintf 或者你可以用这个要点

var print = console.log;

function dformat(str, ...arr) {
  return str.replace(/%(\d+)/g, function(_,i) {
    return arr[--i];
  });
}

function wformat(str, dict) {
  return str.replace(/%(\w+)/g, function(_,k) {
    return dict[k];
  });
}

function sformat(str, dict) {
  return str.replace(/\$(\w+)/g, function(_,m) {
    return dict[m];
  });
}

function tformat(str, dict) {
  return str.replace(/\${(\w+)}/g, function(_,m) {
    return dict[m];
  });
}

print(1, dformat("uid:%1, name:%2", 120, "someone") )
print(2, wformat("color: %name", {name: "green"})   )
print(3, sformat("img: $url", {url: "#"})   )
print(4, tformat("${left} ${right}", {right:"1000", left: "7fff"}) )

如果使用node.js, console.log()将format string作为第一个参数:

 console.log('count: %d', count);

我写了一个函数来精确地解决这个问题。

第一个参数是要参数化的字符串。你应该把你的变量放在这个字符串中，就像这样“%s1， %s2，…”% s12”。

其他参数分别是该字符串的参数。

/***
 * @example parameterizedString("my name is %s1 and surname is %s2", "John", "Doe");
 * @return "my name is John and surname is Doe"
 *
 * @firstArgument {String} like "my name is %s1 and surname is %s2"
 * @otherArguments {String | Number}
 * @returns {String}
 */
const parameterizedString = (...args) => {
  const str = args[0];
  const params = args.filter((arg, index) => index !== 0);
  if (!str) return "";
  return str.replace(/%s[0-9]+/g, matchedStr => {
    const variableIndex = matchedStr.replace("%s", "") - 1;
    return params[variableIndex];
  });
}

例子

parameterizedString("my name is %s1 and surname is %s2", "John", "Doe");
// returns "my name is John and surname is Doe"

parameterizedString("this%s1 %s2 %s3", " method", "sooo", "goood");
// returns "this method sooo goood"

如果变量位置在字符串中改变了，这个函数也支持它而不改变函数参数。

parameterizedString("i have %s2 %s1 and %s4 %s3.", "books", 5, "pencils", "6");
// returns "i have 5 books and 6 pencils."

var user = "your name";
var s = 'hello ' + user + ', how are you doing';