convert value of json object from string in array to number using floatparse

Question

I have a array with json objects. some objects properties values I need to convert to number from string. I need to push converted number value json to new list. I tried using floatparse but didnt succeed. code

var json = [{
    "id" : "0", 
    "msg"   : "hi",
    "cost" : "250.24",
    "discount": "10"
},
{
    "id" : "1", 
    "msg"   : "there",
    "cost" : "45.00",
    "discount": "0"
}];

var  json1 = [];

for (var key in json) {
       if (json.hasOwnProperty(key)) {
    
          for (const prop in json[key]) {        
          const parsed = parseFloat(json[key][prop]);              
          res[key][prop] = isNaN(parsed) ? json[key][prop] : parsed;                                        
           //  need to  push  array of modified json object value converted to number from string into json1  
          }
         
       }
    }

Given your json input example, providing the expected json1 output would help. — AlienWithPizza
– AlienWithPizza, Commented Oct 9, 2021 at 6:22

Amin Taghikhani · Accepted Answer · 2021-10-09 06:38:40Z

1

your loop are wrong.

for (var key in json) => when you use loop over an array it's return item index not key

json.hasOwnProperty(key) => your json is an array you don't need to use hasOwnProperty it's for object

I wrote 2 way for you:

*: you can use + for convert string to number.

*: if you want loop over item keys you can use way1, check Object.entries, Object.keys, Object.values methods.

const json = [{
    "id" : "0", 
    "msg"   : "hi",
    "cost" : "250.24",
    "discount": "10"
},
{
    "id" : "1", 
    "msg"   : "there",
    "cost" : "45.00",
    "discount": "0"
}];

//way1
const json1 = json.map((item)=>{
    return Object.entries(item).reduce((pre,[key,value])=>{
        const parsed = +value
        pre[key] = isNaN(parsed) ? value : parsed
        return pre
    },{})
})
console.log('json1',json1)

//way2
const json2 = json.map((item)=>{
    return {
        "id": +item.id,
        "msg": item.msg,
        "cost": +item.cost,
        "discount": +item.discount,
    }
})
console.log('json2',json2)

edited Oct 9, 2021 at 6:38

answered Oct 9, 2021 at 6:28

Amin Taghikhani

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7 Comments

AlienWithPizza Over a year ago

for (var key in json) will give you key (index), not the values, you're thinking for (var key of json)

AlienWithPizza Over a year ago

Run for (var key in [1,2,3]) console.log(key) vs for (var key of [1,2,3]) console.log(key)

Amin Taghikhani Over a year ago

yes i forgot to write index

Steve Over a year ago

yes way 1 works but order of objects is changed. cost becomes 1st. objects are n numbered. dynamic. I need in same order[{ "id" : 0, "msg" : "hi", "cost" : 250.24, "discount": 10 },...]

Amin Taghikhani Over a year ago

yes, because loop over item keys. I wrote way1 like your code. and loop over keys.

|

AlienWithPizza · Accepted Answer · 2021-10-09 07:17:03Z

1

As objects

I prefer a map solution:

var json = [{
    "id": "0",
    "msg": "hi",
    "cost": "250.24",
    "discount": "10"
  },
  {
    "id": "1",
    "msg": "there",
    "cost": "45.00",
    "discount": "0"
  }
];

const json1 = json.map(obj =>
  Object.fromEntries(Object.entries(obj).map(([key, value]) => {
    const parsedValue = parseFloat(value);
    return [
      key,
      isNaN(parsedValue) ? value : parsedValue
    ];
  })));

console.log(json1);

To take it back to loops however:

var json = [{
    "id": "0",
    "msg": "hi",
    "cost": "250.24",
    "discount": "10"
  },
  {
    "id": "1",
    "msg": "there",
    "cost": "45.00",
    "discount": "0"
  }
];

const json1 = [];

for (const obj of json) {
  const mappedObj = {};

  for (const [key, value] of Object.entries(obj)) {
    const parsedValue = parseFloat(value);
    mappedObj[key] = isNaN(parsedValue) ? value : parsedValue;
  }

  json1.push(mappedObj);
}

console.log(json1);

As arrays

var json = [[
    {key:"id", value:"0"},
    {key:"msg", value:"hi"},
    {key:"cost", value:"250.24"},
    {key:"discount", value:"10"}
  ],
  [
    {key:"id", value:"1"},
    {key:"msg", value:"there"},
    {key:"cost", value:"45.00"},
    {key:"discount", value:"0"}
  ]
];

const json1 = json.map(obj =>
  obj.map(({key, value}) => {
    const parsedValue = parseFloat(value);
    return {
      key,
      value: isNaN(parsedValue) ? value : parsedValue
    };
  }));

console.log(json1);

edited Oct 9, 2021 at 7:17

answered Oct 9, 2021 at 6:28

AlienWithPizza

4462 silver badges8 bronze badges

3 Comments

Steve Over a year ago

output is like this[{ cost: 250.24, discount: 10, id: 0, msg: "hi" }, { cost: 45, discount: 0, id: 1, msg: "there" }] not in order

AlienWithPizza Over a year ago

Two things, in my browser, I hit Run code snippet and I get them put out in order [{"id": 0,"msg": "hi","cost": 250.24,"discount": 10},{"id": 1,"msg": "there","cost": 45,"discount": 0}] Second thing you should NOT be relying on property order of js objects. It is not guaranteed, and we've just proven that with different results.

AlienWithPizza Over a year ago

If order matters, I'd suggest a different data structure. Either represent the objects as arrays instead or use a Map. Reference

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