置換する文字列の部分を見つけるための単純な正規表現がありますが、置換関数を使用して必要なアクションを実行する必要があります。
// The array with your strings
var strings = [
'123456_r.xyz',
'12345_32423_131.xyz',
'1235.xyz',
'237213_21_mmm.xyz'
];
// A function that takes a string and a desired length
function addLeadingZeros(string, desiredLength){
// ...and, while the length of the string is less than desired..
while(string.length < desiredLength){
// ...replaces is it with '0' plus itself
string = '0' + string;
}
// And returns that string
return string;
}
// So for each items in 'strings'...
for(var i = 0; i < strings.length; ++i){
// ...replace any instance of the regex (1 or more (+) integers (\d) at the start (^))...
strings[i] = strings[i].replace(/^\d+/, function replace(capturedIntegers){
// ...with the function defined above, specifying 8 as our desired length.
return addLeadingZeros(capturedIntegers, 8);
});
};
// Output to screen!
document.write(JSON.toString(strings));