Javascript正则表达式删除开头和结尾的特定字符串

Question

Base on the following string

for(var i=0;i<${MyVar}.length;i++){ alert(${MyVar}[i]); }

How can I remove the ${ at the beginning and end } in the end of string, so it can be used like this?

for(var i=0;i<MyVar.length;i++){ alert(MyVar[i]); }

I'm creating a component in my system to inject javascript code and execute, but i need to replace the system variables to javascript variable.

  var script = document.createElement("script");
  script.innerHTML = "var ... "; // variables
  script.innerHTML += transformCode(code); // code injected
  document.getElementsByTagName("head")[0].append(script);

I already did the part of creating the variables from an array of objects, something like that:

function variableTransform(variables){
  var html = "";
  for(var key in variables) {
    html += "var "+key+" ='"+variables[key]+"';\n";
  }
  //alert(html);
  return html;
}

Answer 1

Use

.replace(/\$\{(\w+)\}/g, '$1')

See proof

Explanation

--------------------------------------------------------------------------------
  \$                       '$'
--------------------------------------------------------------------------------
  \{                       '{'
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    \w+                      word characters (a-z, A-Z, 0-9, _) (1 or
                             more times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  \}                       '}'

JavaScript:

 const text = 'for(var i=0;i<${MyVar}.length;i++){ alert(${MyVar}[i]); if(${FooBar}) { ${Bazz}(); } }'; console.log(text.replace(/\\$\\{(\\w+)\\}/g, '$1'));

Answer 2

They are string literals so let it do the work for you.

 var variables = 'var FooBar = "Chicken"; var Bazz = "Tuna"; var MyVar = "Dog";'; var codeString = "for(var i=0;i<${MyVar}.length;i++){ alert(${MyVar}[i]); if(${FooBar}) { ${Bazz}(); } }"; var temp = (new Function(variables + " return `" + codeString + "`")()); console.log(temp);