JQuery .attr is not a function for sharepoint page

Question

I need to change the src of image using JQuery.

<a class="cbs-ItemLink" title="2E2" id="ctl00_ctl39_g_590482e6_7a32_435e_bcd5_0662381d98a8_csr1_2lines_pictureLink"> <img class="cbs-Thumbnail" src="/Style%20Library/16x16.ico" alt="2E2" id="ctl00_ctl39_g_590482e6_7a32_435e_bcd5_0662381d98a8_csr1_2lines_picture"> </a>

$("a.cbs-ItemLink img").attr('src','some value')

I have tried many things but it is giving the same error that attr is not a function.

Updated Question:-

Can you help me how to do it for all li tags like

  <li><div class="cbs-Item" data-displaytemplate="Item2Lines"><a class="cbs-ItemLink" title="2E2"><img class="cbs-Thumbnail" src="/Style%20Library/sharepoint-icon-32038-16x16.ico" alt="2E2">            </a><div class="cbs-Detail"><a class="cbs-Line1Link ms-noWrap ms-displayBlock" href="DMS/2E2" title="2E2">2E2</a></div></div</li>`

Answer 1

If attr is not a function then $("a.cbs-ItemLink img") is not returning a DOM element

Check in F12 Console what $("a.cbs-ItemLink img") returns

Possible causes why it is not working inside the page:

• DOM element doesn't exist yet when the code executes

Vanilla JavaScript (no jQuery required)

(More typing, saves you the hassle of loading a 90 KB library)

check value in the F12 console

document.querySelector("a.cbs-ItemLink img")

Should return DOM element

assign value

document.querySelector("a.cbs-ItemLink img").src = 'some value';