LibJS: Add parseFloat()

Libraries/LibJS/Runtime/GlobalObject.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020, Linus Groh <mail@linusgroh.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -82,6 +83,7 @@ void GlobalObject::initialize()
     put_native_function("gc", gc, 0, attr);
     put_native_function("isNaN", is_nan, 1, attr);
     put_native_function("isFinite", is_finite, 1, attr);
+    put_native_function("parseFloat", parse_float, 1, attr);
 
     put("NaN", js_nan(), 0);
     put("Infinity", js_infinity(), 0);
@@ -140,4 +142,17 @@ Value GlobalObject::is_finite(Interpreter& interpreter)
     return Value(interpreter.argument(0).to_number().is_finite_number());
 }
 
+Value GlobalObject::parse_float(Interpreter& interpreter)
+{
+    auto string = interpreter.argument(0).to_string(interpreter);
+    if (interpreter.exception())
+        return {};
+    for (size_t length = string.length(); length > 0; --length) {
+        auto number = Value(js_string(interpreter, string.substring(0, length))).to_number();
+        if (!number.is_nan())
+            return number;
+    }
+    return js_nan();
+}
+
 }

Libraries/LibJS/Runtime/GlobalObject.h

@@ -58,6 +58,7 @@ private:
     static Value gc(Interpreter&);
     static Value is_nan(Interpreter&);
     static Value is_finite(Interpreter&);
+    static Value parse_float(Interpreter&);
 
     Shape* m_empty_object_shape { nullptr };
 

Libraries/LibJS/Tests/parseFloat.js

@@ -0,0 +1,71 @@
+load("test-common.js");
+
+try {
+    const NUMBER_TEST_CASES = [
+        [0, 0],
+        [1, 1],
+        [.23, 0.23],
+        [1.23, 1.23],
+        [0.0123E+2, 1.23],
+        [1.23e4, 12300],
+        [Infinity, Infinity]
+    ];
+
+    NUMBER_TEST_CASES.forEach(test => {
+        const value = test[0];
+        const result = test[1];
+        assert(parseFloat(value) === result);
+        assert(parseFloat(+value) === result);
+        assert(parseFloat(-value) === -result);
+    });
+
+    const STRING_TEST_CASES = [
+        ["0", 0],
+        ["1", 1],
+        [".23", 0.23],
+        ["1.23", 1.23],
+        ["0.0123E+2", 1.23],
+        ["1.23e4", 12300],
+        ["Infinity", Infinity]
+    ];
+
+    STRING_TEST_CASES.forEach(test => {
+        const value = test[0];
+        const result = test[1];
+        assert(parseFloat(value) === result);
+        assert(parseFloat(`+${value}`) === result);
+        assert(parseFloat(`-${value}`) === -result);
+        assert(parseFloat(`${value}foo`) === result);
+        assert(parseFloat(`+${value}foo`) === result);
+        assert(parseFloat(`-${value}foo`) === -result);
+        assert(parseFloat(`   \n  \t ${value} \v  foo   `) === result);
+        assert(parseFloat(`   \r -${value} \f \n\n  foo   `) === -result);
+        assert(parseFloat({ toString: () => value }) === result);
+    });
+
+    const NAN_TEST_CASES = [
+        "",
+        [],
+        [],
+        true,
+        false,
+        null,
+        undefined,
+        NaN,
+        "foo123",
+        "foo+123",
+        "fooInfinity",
+        "foo+Infinity"
+    ];
+
+    assert(isNaN(parseFloat()));
+    assert(isNaN(parseFloat("", 123, Infinity)));
+
+    NAN_TEST_CASES.forEach(value => {
+        assert(isNaN(parseFloat(value)));
+    });
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e)
+}