viewpoint-js-core

Core types for the viewpoint-js macro, providing the ToJsValue trait for converting Rust values to JavaScript representations, and utilities for escaping strings for use in JavaScript.

This crate is part of the Viewpoint browser automation framework.

Features

• ToJsValue trait: Convert Rust types to JavaScript value strings
• String escaping: Properly escape strings for JavaScript contexts
• CSS attribute escaping: Escape values for CSS attribute selectors
• JSON support: Optional serde_json::Value conversion (with json feature)

Installation

Add to your Cargo.toml:

[dependencies]
viewpoint-js-core = "0.2"

For JSON support:

[dependencies]
viewpoint-js-core = { version = "0.2", features = ["json"] }

Quick Start

use viewpoint_js_core::{ToJsValue, escape_js_string};

// Convert Rust values to JavaScript representation
assert_eq!(42.to_js_value(), "42");
assert_eq!(true.to_js_value(), "true");
assert_eq!("hello".to_js_value(), r#""hello""#);

// Escape a string for JavaScript
assert_eq!(escape_js_string("line1\nline2"), r#""line1\nline2""#);

The ToJsValue Trait

The ToJsValue trait converts Rust values to their JavaScript representations. It's used by the js! macro for value interpolation (#{expr}):

use viewpoint_js_core::ToJsValue;

// Integers
assert_eq!(42i32.to_js_value(), "42");
assert_eq!((-17i64).to_js_value(), "-17");

// Floats
assert_eq!(3.14f64.to_js_value(), "3.14");
assert_eq!(f64::INFINITY.to_js_value(), "Infinity");
assert_eq!(f64::NAN.to_js_value(), "NaN");

// Booleans
assert_eq!(true.to_js_value(), "true");
assert_eq!(false.to_js_value(), "false");

// Strings (properly quoted and escaped)
assert_eq!("hello".to_js_value(), r#""hello""#);
assert_eq!("say \"hi\"".to_js_value(), r#""say \"hi\"""#);
assert_eq!("line1\nline2".to_js_value(), r#""line1\nline2""#);

// Option types
assert_eq!(Some(42).to_js_value(), "42");
assert_eq!(None::<i32>.to_js_value(), "null");

String Escaping Functions

escape_js_string - Double-Quoted Strings

Escapes a string for use in a double-quoted JavaScript string literal:

use viewpoint_js_core::escape_js_string;

assert_eq!(escape_js_string("hello"), r#""hello""#);
assert_eq!(escape_js_string("it's fine"), r#""it's fine""#);  // Single quotes preserved
assert_eq!(escape_js_string(r#"say "hi""#), r#""say \"hi\"""#);  // Double quotes escaped
assert_eq!(escape_js_string("tab\there"), r#""tab\there""#);

escape_js_string_single - Single-Quoted Strings

Escapes a string for use in a single-quoted JavaScript string literal:

use viewpoint_js_core::escape_js_string_single;

assert_eq!(escape_js_string_single("hello"), "'hello'");
assert_eq!(escape_js_string_single("it's"), r"'it\'s'");  // Single quotes escaped
assert_eq!(escape_js_string_single(r#"say "hi""#), r#"'say "hi"'"#);  // Double quotes preserved

escape_js_contents - Without Quotes

Escapes string contents without adding surrounding quotes:

use viewpoint_js_core::escape_js_contents;

assert_eq!(escape_js_contents("hello"), "hello");
assert_eq!(escape_js_contents("line1\nline2"), r"line1\nline2");
assert_eq!(escape_js_contents(r#"say "hi""#), r#"say \"hi\""#);

escape_for_css_attr - CSS Attribute Selectors

Escapes a string for use in CSS attribute selectors within JavaScript:

use viewpoint_js_core::escape_for_css_attr;

// For: document.querySelector('[data-testid="submit-button"]')
let attr_value = escape_for_css_attr("submit-button");
assert_eq!(attr_value, r#"\"submit-button\""#);

// Use in a format string:
let selector = format!(r#"document.querySelector('[data-testid={}]')"#, attr_value);
assert_eq!(selector, r#"document.querySelector('[data-testid=\"submit-button\"]')"#);

Implementing ToJsValue for Custom Types

You can implement ToJsValue for your own types:

use viewpoint_js_core::{ToJsValue, escape_js_string};

struct User {
    name: String,
    age: u32,
}

impl ToJsValue for User {
    fn to_js_value(&self) -> String {
        format!(
            r#"{{ name: {}, age: {} }}"#,
            escape_js_string(&self.name),
            self.age
        )
    }
}

let user = User { name: "John".to_string(), age: 30 };
assert_eq!(user.to_js_value(), r#"{ name: "John", age: 30 }"#);

Integration with Viewpoint

This crate is used internally by viewpoint-js for the js! macro. Most users should use viewpoint-js directly rather than this crate.

License

MIT