Question

I have the following function, which successfully increases the value of input type="text"

function deleteLine(arrayNumber) {
    $("#line" + arrayNumber + "_quantity").val(parseInt($("#line" + arrayNumber + "_quantity").val()) + 1);
}

I’m just wondering why these don’t work instead, for a neater code:

$("#line" + arrayNumber + "_quantity").val(this + 1);
$("#line" + arrayNumber + "_quantity").val(this.value + 1);
$("#line" + arrayNumber + "_quantity").val($(this).val() + 1);

Answer 1

You should try like below,

$("#line" + arrayNumber + "_quantity").val(function (i, v) { return +v+1; });

Your version doesn’t work because the this doesn’t refer to the textbox.

Thanks @FelixKing for the unary operator.