Javascript中的拆分功能不适用于对象的字符串

Question

Giving this in js:

let data={"vets":[{"id": 1,"lt": "6","ln": 2702,"ls": "2011-07-02T00:00:00"}]};

I want to use the split() function on the ls property.

data['vets'].ls is giving the value: "2011-07-02T00:00:00".

I save it to a variable like this:

let str = data['vets'].ls;

When i run str.split('T')[0] to get only 2011-07-02 , i get an error of:

Uncaught TypeError: Cannot read property 'split' of null

Edit: The array i have is about 3000 items. I am using the map() functionn to go on all of them like this:

data['vets'].map(function(vet){
   let str = vet['ls'];
   let short = str.split('T');
   vet['ls'] = short[0];
})

What can be the reason for it? Thanks.

Answer 1

Try data['vets'][0].ls.split('T')[0] .

In other words, you need to first access the first child of the data[vets] array and perform a split on its ls field. What you are doing instead, is calling split on an ls property of the array itself, which is indeed undefined .

To get only the "date" part from each item:

 let data = {"vets":[{"id": 1,"lt": "6","ln": 2702,"ls": "2011-07-02T00:00:00"}]}; console.log(data.vets.map(entry => entry.ls.split('T')[0])); // shorter version which does the same thing console.log(data.vets.map(({ ls }) => ls.split('T')[0])); 

To create a new array of items with modified ls fields:

 let data = {"vets":[{"id": 1,"lt": "6","ln": 2702,"ls": "2011-07-02T00:00:00"}]}; // splits every item into two variables: `ls` and `rest`. `ls` is a string, // whereas `rest` is an object containing all of the fields of the original // item. Using these variables, modified objects are created and assembled // into a new array in an immutable way (the original data is not altered) console.log(data.vets.map(({ ls, ...rest }) => ({ // replaces the `ls` field's value ls: ls.split('T')[0], // includes all the other properties untouched ...rest, })));