Pass parameter as an array element

Question

I'd like to pass an array element as a parameter to my function.

I have an array and my array has Column1 and Column2 elements. My code is sorting the array according to column1 or column2. Right now, I'm passing the 1 and 2 values as a parameter and I have an if condition in my sorting code.

I want to change my code like:

function sortGrid(ColumnName)

and

var val1 = a.ColumnName.toLowerCase()

Do you have any suggestions?

Code:

<html lang="">
<body>

<script>
var arr = [{"Column1":"A","Column2":"F"},{"Column1":"Z","Column2":"B"}];

    function sortGrid(col) {
        arr.sort(function (a, b) {
            if (col == 1)
            {
                var val1 = a.Column1.toLowerCase();
                var val2 = b.Column1.toLowerCase();
            };
            if (col == 2)
            {
                var val1 = a.Column2.toLowerCase();
                var val2 = b.Column2.toLowerCase();
            };

            if (val1 < val2)
                return -1
            if (val1 > val2)
                return 1
        });
    }

    sortGrid(1)
    console.log(arr[0].Column1)
    console.log(arr[1].Column1)

    console.log('-------------------')

    sortGrid(2)
    console.log(arr[0].Column1)
    console.log(arr[1].Column1)


</script>
</body>
</html>

Instead of a.ColumnName (which wont work), do a[ColumnName]: that is the dynamic way. — trincot
– trincot, Commented Jul 15, 2016 at 14:47

trincot · Accepted Answer · 2016-07-15 14:50:45Z

1

You can do that with a[ColumnName]:

var arr = [{"Column1":"A","Column2":"F"},{"Column1":"Z","Column2":"B"}];

function sortGrid(colName) {
  arr.sort(function (a, b) {
    var val1 = a[colName].toLowerCase();
    var val2 = b[colName].toLowerCase();
    return   val1 < val2 ? -1
           : val1 > val2 ? 1
           : 0;
  });
}

sortGrid('Column1')
console.log(arr[0].Column1)
console.log(arr[1].Column1)

console.log('-------------------')

sortGrid('Column2')
console.log(arr[0].Column1)
console.log(arr[1].Column1)

Note that you should return 0 when the values are equal, so I have used the ternary operator (twice) with a 0 in it as well.

answered Jul 15, 2016 at 14:50

trincot

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2 Comments

Gurcan Over a year ago

Thank you very much. it is working. Btw, how could you add this run code snippet button? Can you explain it please?

trincot Over a year ago

When you put a question or answer there is a series of buttons at the top (bold, italic, ...). The rightmost of those allows you to create a snippet: it opens a popup in which you can put your JS, HTML, CSS and when you confirm it injects some special  tags inside your text which will do the trick.

Pablo Lozano · Accepted Answer · 2016-07-15 14:50:33Z

Your code could be something like:

var arr = [{"Column1":"A","Column2":"F"},{"Column1":"Z","Column2":"B"}];

function sortGrid(colName) {
    arr.sort(function (a, b) {
       var val1 = a[colName].toLowerCase();
       var val2 = b[colName].toLowerCase();
       if (val1 < val2)
            return -1
        if (val1 > val2)
            return 1
    });
}

sortGrid('Column1')
console.log(arr[0].Column1)
console.log(arr[1].Column1)

console.log('-------------------')

sortGrid('Column2')
console.log(arr[0].Column1)
console.log(arr[1].Column1)

Just one more thing: if you use var to declare local variables, then their scope is the whole function, so your code is declaring them twice. It will work but is unnecessary.

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