JS method of extracting numbers from strings

1 parseInt() Method ：

	var str ="4500 element "; 
	
    var num = parseInt(str);
    
    alert(num);//4500 

The result is what we want , Thought it was so simple , It would be wrong . If the string is preceded by a non numeric character , The above method will not work ：

	var str =" Price ：4500 element ";
	 
    var num = parseInt(str);
    
    alert(num);//NaN

This example will pop up NaN, Solve this problem , The easiest way is ： If you know the string format , Remove the preceding non characters . In the example above , Remove substring " Price ："

	var str =" Price :4500 element ";

    var num = parseInt(str.substring(1).substring(1).substring(1));
      
    alert(num);//4500 

obviously , This is more troublesome .Js Medium parseInt() Method can pass a non numeric string , As long as the string is preceded, it runs the same , Know to stop when you encounter non numeric characters . such as , Here's an example .

	var str ="4500 element , Grade ：2";

    var num = parseInt(str);
  
    alert(num);//4500

2. Regular

in fact , Regular processing is relatively simple , Just replace non numeric characters . Example ：

	var s =" Price 4500 element ";

    var num= s.replace(/[^0-9]/ig,"");

    alert(num);//4500

If you encounter characters with numbers ：

	var s =" Price 4500 element , Grade ：2";

    var num = s.replace(/[^0-9]/ig,"");

    alert(num);//45002