How can I convert a JavaScript object into a string?
Example:
var o = {a:1, b:2}
console.log(o)
console.log(\'Item: \' + o)
Output:
By using below replacer we can produce less redundant JSON - if source object contains multi-references to some object, or contains circular references - then we reference it by special path-string (similar to JSONPath) - we use it as follows
let s = JSON.stringify(obj, refReplacer());
function refReplacer() {
let m = new Map(), v= new Map(), init = null;
return function(field, value) {
let p= m.get(this) + (Array.isArray(this) ? `[${field}]` : '.' + field);
let isComplex= value===Object(value)
if (isComplex) m.set(value, p);
let pp = v.get(value)||'';
let path = p.replace(/undefined\.\.?/,'');
let val = pp ? `#REF:${pp[0]=='[' ? '$':'$.'}${pp}` : value;
!init ? (init=value) : (val===init ? val="#REF:$" : 0);
if(!pp && isComplex) v.set(value, path);
return val;
}
}
// ---------------
// TEST
// ---------------
// gen obj with duplicate references
let a = { a1: 1, a2: 2 };
let b = { b1: 3, b2: "4" };
let obj = { o1: { o2: a }, b, a }; // duplicate reference
a.a3 = [1,2,b]; // circular reference
b.b3 = a; // circular reference
let s = JSON.stringify(obj, refReplacer(), 4);
console.log(s);
BONUS: and here is inverse function of such serialisation
function parseRefJSON(json) {
let objToPath = new Map();
let pathToObj = new Map();
let o = JSON.parse(json);
let traverse = (parent, field) => {
let obj = parent;
let path = '#REF:$';
if (field !== undefined) {
obj = parent[field];
path = objToPath.get(parent) + (Array.isArray(parent) ? `[${field}]` : `${field?'.'+field:''}`);
}
objToPath.set(obj, path);
pathToObj.set(path, obj);
let ref = pathToObj.get(obj);
if (ref) parent[field] = ref;
for (let f in obj) if (obj === Object(obj)) traverse(obj, f);
}
traverse(o);
return o;
}
// ------------
// TEST
// ------------
let s = `{
"o1": {
"o2": {
"a1": 1,
"a2": 2,
"a3": [
1,
2,
{
"b1": 3,
"b2": "4",
"b3": "#REF:$.o1.o2"
}
]
}
},
"b": "#REF:$.o1.o2.a3[2]",
"a": "#REF:$.o1.o2"
}`;
console.log('Open Chrome console to see nested fields:');
let obj = parseRefJSON(s);
console.log(obj);