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Regular Expression & rgb2hex

regex

// 颜色字符串转换
function rgb2hex(sRGB = 'rgb(255, 255, 255)') {
  const temp = sRGB;
  // /^rgb([s*d+,]{2}[s*d+])$/
  if(/^rgb([s*d+,]{2}[s*d+]{1})$/.test(temp)) {
    // 符合 rgb 格式
  } else {
    // 输入不符合 rgb 格式，返回原始输入
    return temp;
  }
}

function rgb2hex (sRGB = 'rgb(255, 255, 255)') {
  const regex = /^(rgb|RGB)((d{1,3}),s*(d{1,3}),s*(d{1,3}))/;
  if(!regex.test(sRGB)){
    return sRGB;
  }else {
    function hex(str) {
      // string < number ❓⚠️
      return str < 16 ? "0" + Number(str).toString(16) : Number(str).toString(16);
    }
    return sRGB.replace(regex, function(a, c, r, g, b){
      console.log(`a, c`, a, c);
      console.log(`r, g, b`, r, g, b);
      console.log(`typeof r, typeof g, typeof b`, typeof r, typeof g, typeof b);
      // console.log(`a, c, r, g, b`, a, c, r, g, b);
      return "#" + hex(r) + hex(g) + hex(b);
    })
  }
}


function rgb2hex (sRGB = 'rgb(255, 255, 255)') {
  const rgbStr = sRGB.toLowerCase();
  // rgb 50%, RGB 50%
  const regex = /^(rgb|RGB)((d{1,3}),s*(d{1,3}),s*(d{1,3}))/;
  // const regex = /^rgb((d{1,3}),s*(d{1,3}),s*(d{1,3}))/;
  if(!regex.test(rgbStr)){
    return sRGB;
  }else {
    function hex(str) {
      return str < 16 ? "0" + Number(str).toString(16) : Number(str).toString(16);
    }
    return rgbStr.toLowerCase().replace(regex, function(a, c, r, g, b){
      console.log(`a, c`, a, c);
      console.log(`r, g, b`, r, g, b);
      // console.log(`a, c, r, g, b`, a, c, r, g, b);
      return "#" + hex(r) + hex(g) + hex(b);
    })
  }
}

refs

https://regexper.com/

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Cheatsheet

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