一个简单的stringFormat

function stringFormat(format, args) {
    var formatData;
    if (arguments.length == 2 && args && typeof(args) == "object") {
        formatData = args;
    } else {
        formatData = Array.prototype.slice.call(arguments, 1);
    }
    var pattern = [];
    for (var key in formatData) {
        pattern.push("\\{" + key + "\\}");
    }
    if (!pattern.length) {
        return format;
    }
    pattern = pattern.join("|");
    return format.replace(new RegExp(pattern, "img"),
    function(matchValue, index, inputString) {
        var key = matchValue.slice(1, -1);
        return formatData[key];
    });
}

function stringFormat() {
    var data, args = arguments,
    arr = [],
    i = 0;
    data = (args.length == 2 && args[1] && typeof(args[1]) == "object") ? args[1] : Array.prototype.slice.call(args, 1);
    for (arr[i++] in data);
    return arr.length ? args[0].replace(new RegExp("\\{" + arr.join("\\}|\\{") + "\\}", "img"),
    function(val) {
        return data[val.slice(1, -1)];
    }) : args[0];
}

stringFormat(); // undefined
stringFormat("1 {0} 3 {1}"); //"1 {0} 3 {1}"
stringFormat("1 {0} 3 {1}", 2); //"1 2 3 {1}"
stringFormat("1 {0} 3 {1}", 2, 4); //"1 2 3 4"
stringFormat("1 {0} 3 {1}", [2, 4]); //"1 2 3 4"
stringFormat("1 {0} 3 {1}", [2]); //"1 2 3 {1}"
stringFormat("1 {a} 3 {b}", { a: 2, b: 4}); //"1 2 3 4"
stringFormat("1 {a} 3 {b}", {  a: 2}); //"1 2 3 {b}"
stringFormat("1 {a} 3 {b}", {  a: 2,  b: 4},1, 2); //"1 {a} 3 {b}"
stringFormat("1 {0} 3 {1}", [2, 4], 4, 5); //"1 2,4 3 4"
```
##示例2
```
//多行的写法 加 ‘\‘
var mLine = "My name is {name},I am {age}.                    My name is {name},I am {age}.                    My name is {name},I am {age}.";

stringFormat(mLine, {   name: ‘lranye‘,    age: 12});
/*结果：
My name is lranye,
I am 12.My name is lranye,
I am 12.My name is lranye,
I am 12.
*/

//执行：
stringFormat(mLine, { name: ‘{age}‘,  age: 12});
/*结果：
My name is { age},
I am 12.My name is {age},
I am 12.My name is { age},
I am 12.
*/