Using GreaseKit: if a string is present in a table cell, then click a specific button IF it appears in the very same cell

Question

I am using GreaseKit (so JavaScript)

Step #1 Look for string & Step #2 Click button

When this HTML page loads, if either of the following :

• Only 3 Left or
• Only 2 Left or
• Only 1 Left

appears in a table cell AND a button with class="PrmryBtnMed" is present in that very same cell, then click the button using el.click();

Can we just look inside the <tr> tags?

If not, an alternative approach might be to just click the first button that appears immediately underneath, or after the desired string.

update: thanks to @Bergi, it seems we can just use: var LookInCells = document.getElementsByTagName('tr');

About that button: which attribute to look for?

the bit of html looks like: <a href="/gp/wine/taste-next-123/" class="PrmryBtnMed" id = "product-B00123456"><span>Send me this item</span></a>

So, thinking about attributes of the button

These will always be the same:

• class="PrmryBtnMed"
• <span>Send me this item</span></a>

These will always vary, so might as well ignore:

• where the link points to (e.g. a href="/gp/wine/taste-next/")
• the id will always be 'id = "product-B00123456"'

Answer 1

I'm having a go at this based on the kind guidance of @Bergi!

var LookInCells = document.getElementsByTagName('tr');
var MyString =  ['Only 3 Left', 'Only 2 Left', 'Only 1 Left']
for(var i = 0;i < LookInCells.length;i++){
}

var inPage = document.documentElement.innerHTML.indexOf(MyString) > 0,
// el = document.querySelector(".PrmryBtnMed");
el = document.getQuerySelectorAll("td:last-child a.PrmryBtnMed")    
if (inPage && el) el.click();