I'm stringyfing an object like {'foo': 'bar'}
How can I turn the string back to an object?
This question is related to
javascript
json
object
$("#save").click(function () {
debugger
var xx = [];
var dd = { "firstname": "", "lastname": "", "address": "" };
var otable1 = $("#table1").dataTable().fnGetData();
for (var i = 0; i < otable1.length; i++) {
dd.firstname = otable1[i][0];
dd.lastname = otable1[i][1];
dd.address = otable1[i][2];
xx.push(dd);
var dd = { "firstname": "", "lastname": "", "address": "" };
}
JSON.stringify(alert(xx));
$.ajax({
url: '../Home/save',
type: 'POST',
data: JSON.stringify({ u: xx }),
contentType: 'application/json;',
dataType: 'json',
success: function (event) {
alert(event);
$("#table2").dataTable().fnDraw();
location.reload();
}
});
});
Check this out.
http://jsfiddle.net/LD55x/
Code:
var myobj = {};
myobj.name="javascriptisawesome";
myobj.age=25;
myobj.mobile=123456789;
debugger;
var str = JSON.stringify(myobj);
alert(str);
var obj = JSON.parse(str);
alert(obj);
JSON.parse
is the opposite of JSON.stringify
.
how about this partial solution?
I wanna store (using a Config node) a global bigobj, with data + methods (as an alternative to importing an external library), used in many function nodes on my flow:
Strange but it works: The global variable 'bigobj':
{
some[]more[]{dx:"here"} , // array of objects with array of objects. The 'Config' node requires JSON.
.....
"get_dx": "function( d,p) { return this.some[d].more[p].dx; }" // test function
}
i.e. a JSON version of a function.... (all in one line :( )
USE: Inside a function node:
var bigO = global.get("bigobj");
function callJSONMethod(obj, fname, a, b, c, d){
// see: https://stackoverflow.com/questions/49125059/how-to-pass-parameters-to-an-eval-based-function-injavascript
var wrap = s => "{ return " + obj[fname] + " };" //return the block having function expression
var func = new Function(wrap(obj[fname]));
return func.call( null ).call( obj, a, b, c, d); //invoke the function using arguments
}
msg.payload =callJSONMethod(bigO, "get_dx", 2, 2);
return msg:
returns "here", unbelieve!
i.e I must add the function callJSONMethod() to any function block using bigobj..... maybe acceptable.
Best regards
How about this
var parsed = new Function('return ' + stringifiedJSON )();
This is a safer alternative for eval
.
var stringifiedJSON = '{"hello":"world"}';_x000D_
var parsed = new Function('return ' + stringifiedJSON)();_x000D_
alert(parsed.hello);
_x000D_
http://jsbin.com/tidob/1/edit?js,console,output
The native JSON object includes two key methods.
1. JSON.parse()
2. JSON.stringify()
The JSON.parse()
method parses a JSON string - i.e. reconstructing the original JavaScript object
var jsObject = JSON.parse(jsonString);
JSON.stringify() method accepts a JavaScript object and returns its JSON equivalent.
var jsonString = JSON.stringify(jsObject);
Recommended is to use JSON.parse
There is an alternative you can do :
var myObject = eval('(' + myJSONtext + ')');
JSON.stringify
and JSON.parse
are almost oposites, and "usually" this kind of thing will work:
var obj = ...;
var json = JSON.stringify(obj);
var obj2 = JSON.parse(json);
so that obj and obj2 are "the same".
However there are some limitations to be aware of. Often these issues dont matter as you're dealing with simple objects. But I'll illustrate some of them here, using this helper function:
function jsonrepack( obj ) { return JSON.parse(JSON.stringify(obj) ); }
You'll only get ownProperties
of the object and lose prototypes:
var MyClass = function() { this.foo="foo"; }
MyClass.prototype = { bar:"bar" }
var o = new MyClass();
var oo = jsonrepack(o);
console.log(oo.bar); // undefined
console.log( oo instanceof MyClass ); // false
You'll lose identity:
var o = {};
var oo = jsonrepack(o);
console.log( o === oo ); // false
Functions dont survive:
jsonrepack( { f:function(){} } ); // Returns {}
Date objects end up as strings:
jsonrepack(new Date(1990,2,1)); // Returns '1990-02-01T16:00:00.000Z'
Undefined values dont survive:
var v = { x:undefined }
console.log("x" in v); // true
console.log("x" in jsonrepack(v)); // false
Objects that provide a toJSON
function may not behave correctly.
x = { f:"foo", toJSON:function(){ return "EGAD"; } }
jsonrepack(x) // Returns 'EGAD'
I'm sure there are issues with other built-in-types too. (All this was tested using node.js so you may get slightly different behaviour depending on your environment too).
When it does matter it can sometimes be overcome using the additional parameters of JSON.parse
and JSON.stringify
. For example:
function MyClass (v) {
this.date = new Date(v.year,1,1);
this.name = "an object";
};
MyClass.prototype.dance = function() {console.log("I'm dancing"); }
var o = new MyClass({year:2010});
var s = JSON.stringify(o);
// Smart unpack function
var o2 = JSON.parse( s, function(k,v){
if(k==="") {
var rv = new MyClass(1990,0,0);
rv.date = v.date;
rv.name = v.name;
return rv
} else if(k==="date") {
return new Date( Date.parse(v) );
} else { return v; } } );
console.log(o); // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o.constructor); // [Function: MyClass]
o.dance(); // I'm dancing
console.log(o2); // { date: <Mon Feb 01 2010 ...>, name: 'an object' }
console.log(o2.constructor) // [Function: MyClass]
o2.dance(); // I'm dancing
Source: Stackoverflow.com