如何通过循环使此jQuery函数更有效？

Question

I need to use jQuery to find elements, get their nested paragraph and then add in a div before this paragraph. I have it working fine, but it's very repetitive code and I want to make it more efficient and tidy it up, but I'm not sure how.

Here is the code:

$(".container .row").each(function(index) {
    var row1,
        row2,
        row3,
        row4,
        newRow1,
        newRow2,
        newRow3,
        newRow4;

    row1 = jQuery(this).find(".elementA");
    row2 = jQuery(this).find(".elementB");
    row3 = jQuery(this).find(".elementC");
    row4 = jQuery(this).find(".elementD");

    newRow1 = row1.find("p");
    newRow2 = row2.find("p");
    newRow3 = row3.find("p");
    newRow4 = row4.find("p");

    $("<div>Test 1</div>").insertBefore(newRow1);
    $("<div>Test 1</div>").insertBefore(newRow2);
    $("<div>Test 1</div>").insertBefore(newRow3);
    $("<div>Test 1</div>").insertBefore(newRow4);

    return;
});

Answer 1

1. Take the div html string outside of the loop
2. You can remove all the variables
3. Cache this context
4. return at the end is not necessary

Code:

var div = "<div>Test 1</div>";
$(".container .row").each(function (index) {
    var $this = jQuery(this);

    $(div).insertBefore($this.find(".elementA p"));
    $(div).insertBefore($this.find(".elementB p"));
    $(div).insertBefore($this.find(".elementC p"));
    $(div).insertBefore($this.find(".elementD p"));
});

You can also shorten your code as follow if you want to iterate over all the elements whose class starts with element :

var div = "<div>Test 1</div>";
$(".container .row [class^=element] p").each(function () {
    $(div).insertBefore($(this));
});

I'll also suggest you to use the same class name to all the elements instead of elementX .

Answer 2

Looks like normal selectors can reduce the load.

$(".container .row").each(function (index) {
    var newRow = jQuery(this).find(".elementA p, .elementB p, .elementC p, .elementD p");
    $("<div>Test 1</div>").insertBefore(newRow);
    return;
});