TypeScript: find values of certain keys in JSON

Question

I have a JSON that contains a lot of data, here's an example of it:

{
   "type":"doc",
   "content":[
      {
         "type":"paragraph",
         "content":[
            {
               "text":"this is a simple page, about a simple umbrella.",
               "type":"text"
            }
         ]
      },
      {
         "type":"paragraph",
         "content":[
            {
               "text":"you can use this text to find the umbrella page.",
               "type":"text"
            }
         ]
      },
      {
         "type":"paragraph",
         "content":[
            {
               "text":"do you like it?",
               "type":"text"
            }
         ]
      }
}

I want to extract the value of text key, no matter where the key is located. I'm trying to go over the keys using Object.keys but it only returns the top-level keys:

for (let x of Object.keys(someJson)) {
    console.log(x);
}

How can I find all the values of text in this JSON, no matter where in the JSON it is?

you need to use recursion

captain-yossarian from Ukraine
– captain-yossarian from Ukraine

2021-10-27 08:33:48 +00:00
Commented Oct 27, 2021 at 8:33 — captain-yossarian from Ukraine
– captain-yossarian from Ukraine, Commented Oct 27, 2021 at 8:33

MJ Studio · Accepted Answer · 2021-10-27 08:34:09Z

1

You can use JSON.stringify trick, you can intercept all keys from it

function find(obj: object, key: string) {
  const ret: any[] = [];
  JSON.stringify(obj, (_, nested) => {
    if (nested && nested[key]) {
      ret.push(nested[key]);
    }
    return nested;
  });
  return ret;
};

...

const o = {
  key: '123',
  a: {
    key: 'hello',
    b: [
      {
        c: {
          key: 123,
        },
      },
    ],
  },
};
it('123', () => {
  console.log(JSON.stringify(find(o, 'key'))); // ["123","hello",123]
});

answered Oct 27, 2021 at 8:34

MJ Studio

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Comments

Harsh Kanjariya · Accepted Answer · 2021-10-27 08:35:16Z

0

if you want for generic JSON just call this function and pass your object :

function printText(obj){
    if(Array.isArray(obj)){
        for(const o of obj){
            printText(o);
        }
    }else if(typeof obj === "object"){
        if (obj){
            for(const o of Object.keys(obj)){
                 if(o==="text"){
                      console.log(obj.text);
                 }else{
                      printText(obj[o]);
                 }
            }
        }
    }

}

answered Oct 27, 2021 at 8:35

Harsh Kanjariya

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