javascript - Why can't I use toFixed on an HTML input object's value? -

I have an HTML input element and after trying to change the value of the user, try to force a decimal place in the input I am doing So, let's assume that the user enters "4", I run this code:

  this.value = this.value.toFixed (1)   
 But I get a JavaScript error in which "Object 4 does not have any fixed fixes."  
 It seems JavaScript is trying to process a verb as a number, but, er, why? And how can I avoid it?   
 
 
  this.value  is a  string  You get it from an input element before you can use the numbering methods on it, it needs to be placed on the number:  
  this.value = number (this. Value) .toFixed (1);   
 Alternatively, you can use the unary  +  operator to put the string on the number:  
  this. Value (+ this .value) .toFixed (1);   
 If you need to remove the string suffix, you can use  parseFloat :  
  this.value = ParseFloat (this. Value) .toFixed (1);    
 
    
 However, to handle the hexadecimal format when casting  number   parseFloat   not  Should keep in mind> :  
  this.value = + '0xF'; // 15 this.value = parseFloat ('0xF'); // 0