content script in chrome extension - google-chrome-extension

Question

i have to add div in google search page through chrome extension
my inject.js file is as follow:
var body=document.getElementById("search");
//creates bar and creates bar removal function
var bar = document.createElement("DIV");
function removeBar(){
bar.remove();
}
//styles bar
var ds = bar.style;
ds.position = "fixed";
ds.width = "512px";
ds.height = "33px";
ds.background = "rgba(0,0,0,0.86)";
ds.zIndex = "9999999999999";
//creates X button and makes it so clicking it runs the removeBar() function
var x = document.createElement("BUTTON");
x.onclick = removeBar;
bar.appendChild(x);
//styles button
var xs = x.style;
xs.background = "black";
xs.borderColor = "black";
xs.color = "rgba(255,255,255,.86)";
xs.position = "fixed";
xs.left = "100%";
xs.marginTop = "5px";
xs.marginLeft = "-29px"
//puts X in button
var xtext = document.createTextNode("X");
x.appendChild(xtext);
//puts bar in page
body.insertBefore(bar, body.children[0]);
and my manifest.json is as follow:
{
"manifest_version": 2,
"name": "Inject script in webpage",
"version": "2.0.1",
"description": "inject script in webpage.",
"icons": {
"48" : "sample-48.png",
"128" : "sample-128.png"
},
"content_scripts": [
{
"matches": ["https://www.google.com.pk/*"],
"js" : ["inject.js"],
"all_frames": true
}
]
}
but when i load google SERP page, error message shows somewhat like " cannot call "insertBefore" property of null", it seems that variable "body" is undefined. by inspect element of google page i checked that DIV with ID "search" is present if i am doing it wrong then plzz let me know i am novice in chrome extension development

Answer 1

The problem is probably here:
var body=document.getElementById("search");
the "body" variable is null - probably because the id you're looking for doesn't exist. Try looking for some other id (I used "gbqfb"). But rather than feeding you the answer here, what you should really do is learn to use Chrome's built-in debugger to find out why your code isn't working. Have a look at this youtube video:
https://www.youtube.com/watch?v=htZAU7FM7GI