How to check if hex color is “too black”?

Question

I\'m trying to evaluate the darkness of a color chosen by a color picker to see if it\'s \"too black\", and if so, set it to white. I thought I could use the first character

Answer 1

This work with hex e.g #fefefe

function isTooDark(hexcolor){
    var r = parseInt(hexcolor.substr(1,2),16);
    var g = parseInt(hexcolor.substr(3,2),16);
    var b = parseInt(hexcolor.substr(4,2),16);
    var yiq = ((r*299)+(g*587)+(b*114))/1000;
    // Return new color if to dark, else return the original
    return (yiq < 40) ? '#2980b9' : hexcolor;
}

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You can change it to return true or false by change

return (yiq < 40) ? '#2980b9' : hexcolor;

to

return (yiq < 40);