Typescript strange escape character behavior

Question

Query is similar to the one mentioned in

New to typescript and front end dev. Using Angular form to take input from user which may contain regex.

Example:

this.expressions is actually a input from form multiple expressions can be passed seperated by new line character.

this.rewrite_object = []
this.expressions = "s|.*|{{ date | replace('-', '') }}\"/apps/data/{{ date | replace('-', '/') }}"
this.rewrite_array = this.expressions.split('\n')
console.log("******************Print after split******************")
console.log(this.rewrite_array)
if (this.rewrite_array.length > 0) {
   for(var i = 0;i<this.rewrite_array.length;i++) { 
      if (this.rewrite_array[i]) {
        console.log("******************Print before adding to array******************")
        console.log(this.rewrite_array[i])
        this.rewrite_object.push({ "expression": this.rewrite_array[i] });
        console.log("******************Print rewrite object******************")
        console.log(this.rewrite_object)
      }
   }
}

This is what I get in output. escape character vanish.

******************Print after split******************                                                                                       
[                                                                                                                                           
  `s|.*|{{ date | replace('-', '') }}"/apps/data/{{ date | replace('-', '/') }}`                                                            
]                                                                                                                                           
******************Print before adding to array******************                                                                            
s|.*|{{ date | replace('-', '') }}"/apps/data/{{ date | replace('-', '/') }}                                                                
******************Print rewrite object******************                                                                                    
[                                                                                                                                           
  {                                                                                                                                         
    expression: `s|.*|{{ date | replace('-', '') }}"/apps/data/{{ date | replace('-', '/') }}`                                              
  }                                                                                                                                         
] 

Thought of escaping escape character itself by using \ but this fails with error during compilation.

test.ts:2:70 - error TS1136: Property assignment expected.                                                                                  
                                                                                                                                            
2 this.expressions = "s|.*|{{ date | replace('-', '') }}\\"/apps/data/{{ date | replace('-', '/') }}"                                       
                                                                       ~                                                                    
                                                                                                                                            
test.ts:2:98 - error TS1128: Declaration or statement expected.                                                                             
                                                                                                                                            
2 this.expressions = "s|.*|{{ date | replace('-', '') }}\\"/apps/data/{{ date | replace('-', '/') }}"                                       
                                                                                                   ~                                        
                                                                                                                                            
test.ts:2:100 - error TS1002: Unterminated string literal.                                                                                  

2 this.expressions = "s|.*|{{ date | replace('-', '') }}\\"/apps/data/{{ date | replace('-', '/') }}"
                                                                                                     


Found 3 errors.

How can we make " work with typescript as it's. I need to save this information in DB after taking as input from customer.

Answer 1

You need to escape the backslash but still also escape the double quote: to receive a \" in the final string you have to write \\\" within your doubl-quoted string.

The first \ will escape the second one giving you one literal \ in the resulting string. The third \ escapes the double quote so it will be included in the resulting string and not terminate your string.

this.expressions = "s|.*|{{ date | replace('-', '') }}\\\"/apps/data/{{ date | replace('-', '/') }}"