JS Iterate array of objects and replace values in string

Question

I have an array of javascript objects that I am working with. The keys are dynamically generated and there will be an unknown number of them.

I am trying to loop over the object and replace a piece of data in its value.

Here is an example below:

var obj = [{
    name: 'Joe',
    age: 21,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
},
{
    name: 'Bob',
    age: 25,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
}]


for (var key in obj) {
    if (obj.hasOwnProperty(key)) {
        obj[key].replace(/<br>/g,'\r\n')
    }
}

In the object, I am trying to replace the <br> with \r\n. The column names are not always known.

Should I be doing this through a loop or some type of mapping? Just needing to convert this data before passing it to an excel export where I need to utilize line breaks.

First you will need to loop the array [] then loop the keys.. — Keith
– Keith, Commented Apr 18, 2018 at 22:35

Rahul Desai · Accepted Answer · 2018-04-18 23:23:23Z

Should I be doing this through a loop or some type of mapping?

Yes, you do need a loop. One way to do it is using a combination of both -

a map for looping through the array and returning new array
a for loop in the map to go through all the properties in the object

Working Snippet:

var objArray = [{
    name: 'Joe',
    age: 21,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
  },
  {
    name: 'Bob',
    age: 25,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
  }
];

var newObjArray = objArray.map(function(obj) { // loop through array

  for (var key in obj) { // loop through object properties

    if (typeof obj[key] === 'string') { // only if the value is a string type

      obj[key] = obj[key].replace(/<br>/g, '\r\n'); // same logic as you were using before

    }

  }

  return obj;
});

console.log(newObjArray);

Note: Use map if you do not want to change the original input array but rather generate a new result array. Otherwise, use forEach.

Keith · Accepted Answer · 2018-04-18 22:42:41Z

There are a few issues with your code,..

First you are not traversing the array,. the name obj is slightly misleading here as you have an array.

Also you need to check the type before call replace, eg. the age is a number, it doesn't have a replace method.

And finally when you do call replace you need to store the result, even if it's in the same place.

So taking all these into account, below if you code modified to do what I think your after.

var obj = [{
    name: 'Joe',
    age: 21,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
},
{
    name: 'Bob',
    age: 25,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
}]


for (var i = 0; i < obj.length; i += 1) {
  var obj2 = obj[i];
  for (var key in obj2) {
      if (obj2.hasOwnProperty(key)) {
         if (typeof obj2[key] === "string")
            obj2[key] = obj2[key].replace(/<br>/g,'\r\n')
      }
  }
}
  
console.log(obj);

Taki · Accepted Answer · 2018-04-18 22:42:59Z

0

loop through the objects and use .replace if only it's a string

const obj = [{
    name: 'Joe',
    age: 21,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
  },
  {
    name: 'Bob',
    age: 25,
    randomCol1: 'Blah<br>Blah<br>Blah',
    randomCol2: 'Blah<br>Blah<br>Blah',
    randomCol3: 'Blah<br>Blah<br>Blah'
  }
]


obj.forEach((e) => {

  for (let k in e)
    (e[k] && typeof e[k] == 'string') && (e[k] = e[k].replace(/<br>/g, '\n\r'));

});


console.log(obj)

answered Apr 18, 2018 at 22:42

Taki

17.7k5 gold badges28 silver badges48 bronze badges

Comments

ibrahim tanyalcin · Accepted Answer · 2018-04-18 22:44:29Z

0

A for or while loop will always be faster. But depending on the structure and the size of the array, I'd just do:

obj.forEach(function(d,i){
    Object.keys(d).forEach(function(dd,ii){
        typeof d[dd] === "string" && (d[dd] = d[dd].replace(/<br>/g,'\r\n'))
    })
})

answered Apr 18, 2018 at 22:44

ibrahim tanyalcin

6,5634 gold badges21 silver badges27 bronze badges

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