编写通用字符串替换函数replace, 例如 var a = 'hi, my name is {name}, I am {age} years old, my email is {email}.'; var b = {name:'max', age: 12, email: 'max@gmail.com'}; 执行 replace(a, b) 返回'hi, my name is max, I am 12 years old, my email is max@gmail.com.'

template.js

function template(str, obj) {
  if(str.indexOf('{') === -1) {
    return str;
  }
  var result = [];
  var i, l = str.length;
  var start = 0, end = 0, inner = false;
  var curr, name, value, search;
  for(i = 0; i < l; i++) {
    curr = str[i];

    if(inner) {
      if(curr == '}') {
        name = str.substring(start+1, i);
        if(value = obj[name]) {
          result.push(value);
        } else {
          result.push(name);
        }
        inner = false;
      } else if(curr == '{') {
        search = str.substring(start, i);
        result.push(search);
      }
    } else if(curr != '{' || i == l - 1) { // 当前值不是 '{' 或 最后一个是 '{'
      result.push(curr);
    }

    if(curr == '{') {
      start = i;
      inner = true;
    }
  }
  return result.join('');
}

var a =  '{hi, my name is {name, I am {age} years old, my email is {email}. this is another {name}, test}, {';
var b = {name:'max', age: 12, email: 'max@gmail.com'};

console.log(a);
console.log('');
console.log(template(a, b));