Generate contrast text!!!

getContrasText.js

function setContrastText(hexColor="", isBlackAndWhite=false) {
    if (!hexColor) return "black"
    
    if (hexColor.slice(0, 1) === "#") {
        hexColor = hexColor.slice(1)
    }
    
    if (hexColor.length === 3) {
        hexColor = hexColor.repeat(2)
    }
    
    let r = parseInt(hexColor.substr(0,2),16)
    let g = parseInt(hexColor.substr(2,2),16)
    let b = parseInt(hexColor.substr(4,2),16)
    
    let yiq = ((r * 0.299) + (g * 0.587) + (b * 0.114))
    
    if (isBlackAndWhite) {
        return yiq > 186 ? "#000000" : "#FFFFFF"
    }
    
    r = (255 - r).toString(16)
    g = (255 - g).toString(16)
    b = (255 - b).toString(16)
    
    return `#${padZero(r)}${padZero(g)}${padZero(b)}`
}

function padZero(str, len) {
    len = len || 2;
    var zeros = new Array(len).join('0');
    return (zeros + str).slice(-len);
}