将字符串混合解析为json

Question

I want to parse a string var to json object, however it is not json all the time. If it is not json I want it to be returned as it. I tried JSON.parse, but it will post error when the var is pure string, finally I got JSON.parse(JSON.stringify(var)), I wonder whether there is a way to judge a string can be parse to json or not, so I can save the "stingify" phase.

Answer 1

you can use try / catch. if you get exception when you try to parse it, it means that it is not valid json

var victim=....;
var output;
try { 
   output = JSON.parse(victim); 
} catch (e) { 
   output = victim;
}

Answer 2

There's no better way than actually parsing and knowing if its valid or not. You can use try / catch blocks to set the variable and then return it.

function toJSON(str) {
    var rtn;
    try { rtn = JSON.parse(str); }  // try to set it
    catch (e) { rtn = str; } // if error set it to str
    return rtn;  // finally return
}