javascript TypeError: Cannot find function startsWith

Question

I have a javascript function:

           string.prototype.startsWith = function(str) {
               return (this.indexOf(str) === 0);
           }

and when I run it on something whose typeof returns object, it works. When I run it on something whose typeof returns string, I get:

javax.script.ScriptException: sun.org.mozilla.javascript.internal.EcmaError: TypeError: Cannot find function startsWith. (<Unknown source>#29) in <Unknown source> at line number 29

Does anyone know whats going on? I don't even understand why the instance type of the first thing I'm using is object. It's the result of a readLine call, shouldn't that be string?

<target name="analyze">
    <script language="javascript">

    <![CDATA[
            importClass(java.io.File);
            importClass(java.io.FileReader)
            importClass(java.io.BufferedReader)
            //setup the source directory
            dir = project.getProperty("PROJECT_HOME");
            fs = project.createDataType("fileset");
            fs.setDir(new File(dir));
            //only analyze java files
            fs.setIncludes("**/*.java");
            echo = project.createTask("echo");
            //iterate over files found
            srcFiles = fs.getDirectoryScanner(project).getIncludedFiles();
            for (i = 0; i < srcFiles.length; i++) {
                var filename = srcFiles[i];
                inFile  = new BufferedReader(new FileReader(new File(dir + "/" + filename)));
                while ((line = inFile.readLine()) != null) {
                   if(line.startsWith("package")) {
                       packageStr = line.substr(8);
                       while((line = inFile.readLine()) != null) {
                           if(line.startsWith("import") && line.endsWith("Foo;")) {
                               //strip out the leading import in 'import x.y.z'
                               var importStr = line.substr(7);
                               importStr = importStr.substr(0, importStr.lastIndexOf('.'));
                               if(!importStr.startsWith(packageStr)) { <---- FAILS!
                               }
                           }
                       }
                   }
                }
                inFile.close();
           }

           String.prototype.startsWith = function(str) {
               return (this.indexOf(str) === 0);
           }

           String.prototype.endsWith = function(str) {
               var lastIndex = this.lastIndexOf(str);
               return (lastIndex != -1) && (lastIndex + str.length == this.length);
           }

    ]]>
    </script>
</target>

salman.mirghasemi · Accepted Answer · 2011-06-30 21:04:34Z

3

I think the problem is that you call starstWith function before you define it. Perhaps you should put two function definitions ahead of for block. In this way they are evaluated before they are called.

edited Jun 30, 2011 at 21:04

answered Jun 30, 2011 at 20:57

salman.mirghasemi

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1 Comment

Amir Afghani Over a year ago

That was it! javascript sucks.

moe · Accepted Answer · 2011-06-30 20:31:59Z

2

try with capital S :

String.prototype.startsWith = function(str) {
               return (this.indexOf(str) === 0);
           }

answered Jun 30, 2011 at 20:31

moe

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1 Comment

Amir Afghani Over a year ago

Sorry I should have mentioned that I did both and it didn't work.

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