The static String.raw()
method is a tag function of template literals. This is similar to the r
prefix in Python, or the @
prefix in C# for string literals. (But it is not identical; see explanations in this issue.) It's used to get the raw string form of template strings, that is, substitutions (e.g. ${foo}
) are processed, but escapes (e.g. \n
) are not.
Syntax
String.raw(callSite, ...substitutions)
String.raw`templateString`
Parameters
callSite
- Well-formed template call site object, like
{ raw: ['foo', 'bar', 'baz'] }
. ...substitutions
- Contains substitution values.
templateString
- A template string, optionally with substitutions (
${...}
).
Return value
The raw string form of a given template string.
Exceptions
Description
In most cases, String.raw()
is used with template strings. The first syntax mentioned above is only rarely used, because the JavaScript engine will call this with proper arguments for you, (just like with other tag functions).
String.raw()
is the only built-in tag function of template strings. It works just like the default template function and performs concatenation. You can even re-implement it with normal JavaScript code.
Examples
Using String.raw()
String.raw`Hi\n${2+3}!`; // 'Hi\n5!', the character after 'Hi' // is not a newline character, // '\' and 'n' are two characters. String.raw`Hi\u000A!`; // 'Hi\u000A!', same here, this time we will get the // \, u, 0, 0, 0, A, 6 characters. // All kinds of escape characters will be ineffective // and backslashes will be present in the output string. // You can confirm this by checking the .length property // of the string. let name = 'Bob'; String.raw`Hi\n${name}!`; // 'Hi\nBob!', substitutions are processed. // Normally you would not call String.raw() as a function, // but to simulate `foo${2 + 3}bar${'Java' + 'Script'}baz` you can do: String.raw({ raw: ['foo', 'bar', 'baz'] }, 2 + 3, 'Java' + 'Script'); // 'foo5barJavaScriptbaz' // Notice the first argument is an object with a 'raw' property, // whose value is an iterable representing the separated strings // in the template literal. // The rest of the arguments are the substitutions. // The first argumentβs 'raw' value can be any iterable, even a string! // For example, 'test' is treated as ['t', 'e', 's', 't']. // The following is equivalent to // `t${0}e${1}s${2}t`: String.raw({ raw: 'test' }, 0, 1, 2); // 't0e1s2t'
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'String.raw' in that specification. |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
raw | Chrome Full support 41 | Edge Full support 12 | Firefox Full support 34 | IE No support No | Opera No support No | Safari Full support 10 | WebView Android No support No | Chrome Android Full support 41 | Firefox Android Full support 34 | Opera Android No support No | Safari iOS Full support 10 | Samsung Internet Android Full support 4.0 | nodejs Full support 4.0.0 |
Legend
- Full support
- Full support
- No support
- No support