function abc(){ function chek(x){ x=x-(x%1) if (x<=0){return 0}; if (x>=255){return 255}; return x; } const txt="

Click on the div to generate a random color and its inverted color. Select the checkbox and you can input your RGB values." const finalTxt="

So, by these values, we find that the formula to convert into greyscale is
greyVal=((0.299 * redVal) + (0.587 * greenVal) + (0.114 * blueVal)).
To convert to integer, you can do-
greyVal=greyVal-(greyVal%1).
Then, this greyVal is to be assigned the values of all 3 - Red, Blue and Green.
Note-These decimal numbers are according to how the human eye responds to colors. Note- Some other programs may use some different values to convert to greyscale.Source

" var chk=document.getElementById("chk"); var d1=document.getElementById("d1"); var d2=document.getElementById("d2"); var redInp=document.getElementById("red"); var grInp=document.getElementById("green"); var blInp=document.getElementById("blue"); var out=document.getElementById("out") if(!chk.checked){ var r=Math.floor(Math.random()*256); var g=Math.floor(Math.random()*256); var b=Math.floor(Math.random()*256); }else{ var r=chek(redInp.value) var g=chek(grInp.value) var b=chek(blInp.value) } // 0.299 * color.R + 0.587 * color.G + 0.114 * color.B) var ra = chek((0.299 * r) + (0.587 * g) + (0.114 * b)); d1.style.background=("RGB("+r+","+g+","+b+")"); d2.style.background=("RGB("+ra+","+ra+","+ra+")"); redInp.value=(r); blInp.value=(b); grInp.value=(g); out.innerHTML=(txt+"
Original values -
Red -> "+r+"
Green -> "+g+"
Blue -> "+b+"
Greyscale values -
Red -> "+ra+"
Green -> "+ra+"
Blue ->"+ra+"

If you see, "+ra+" = ((0.299 * "+r+") + (0.587 * "+g+") + (0.114 * "+g+"))
Note - After converting to integer."+finalTxt); } /*function hello(){ alert ( document.getElementsByTagName("input")[0].value); }*/

Tutorial: Greyscale