How does JS-js determine whether a character is Chinese, English, numbers or characters?

//Verify whether it is Chinese
 
var pattern = new RegExp("[\u4E00-\u9FA5]+");
 
var str = "Chinese characters"
 
if(pattern.test(str)){     alert('The string is Chinese' ); } //Verify whether it is English var pattern2 = new RegExp("[A-Za-z]+"); var str2 = "abcdefsgaaweg" if(pattern2.test(str2)){     alert('The string is English'); } //Verify whether it is a number var pattern3 = new RegExp("[0-9]+"); var str3 = "234234" if(pattern3.test(str3)){     alert('The string is Number'); }