Java Script Error Syntax Error
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Syntax Error In C
Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 semantic error million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up How to find Javascript syntax errors [closed] up vote 16 down vote favorite 8 I am writing a JavaScript section
Syntax Error Javascript
of code and am making huge amounts of silly mistakes in the syntax. But the only way to find what line the error is on is to start commenting out the section of code I just wrote and reload it into the browser to narrow down where my missing ');' is. How do you "compile" a JavaScript source to make sure it is syntactically correct so that I can debug it in the math error browser? javascript share|improve this question asked Jan 22 '10 at 19:57 Robert 6,388164870 closed as too broad by Tiny Giant, Drew, Tushar, Alex, Kevin Brown Dec 22 '15 at 14:20 There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question. add a comment| 11 Answers 11 active oldest votes up vote 18 down vote accepted Ctrl + Shift + J in firefox, if you don't catch your mistakes until runtime. Of course firebug works better, but this is a quick way. share|improve this answer answered Jan 22 '10 at 20:12 Carson Myers 15.9k2397144 add a comment| up vote 13 down vote http://www.javascriptlint.com/ Here are some common mistakes that JavaScript Lint looks for: Missing semicolons at the end of a line. Curly braces without an if, for, while, etc. Code that is never run because of a return, throw, continue, or break. Case statements in a switch that do not have a break statement. Leading and trailing decimal points on a number. A leading zero that turns a number into octal (base 8
in
Javascript Code Validator
source code strings. When you type node
Static Semantic Error
src.js you get a friendly error report about exactly where the execution error syntax error is. This module lets you check for syntax errors and report them in a similarly http://stackoverflow.com/questions/2120093/how-to-find-javascript-syntax-errors friendly format that wrapping a try/catch around Function() or vm.runInNewContext() doesn't get you. example var fs = require('fs');var check = require('syntax-error'); var file = __dirname + '/src.js';var src = fs.readFileSync(file); var err = check(src, file);if (err) { console.error('ERROR DETECTED' + Array(62).join('!')); console.error(err); console.error(Array(76).join('-'));} $ node check.jsERROR DETECTED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! /home/substack/projects/node-syntax-error/example/src.js:5 if (Array.isArray(x) res.push.apply(res, x); ^ParseError: Unexpected identifier--------------------------------------------------------------------------- methods var check = require('syntax-error') var err = check(src, file) Check the source code string src for syntax errors. Optionally you can specify https://www.npmjs.com/package/syntax-error a filename file that will show up in the output. If src has a syntax error, return an error object err that can be printed or stringified. If there are no syntax errors in src, return undefined. err.toString() Return the long string description with a source snippet and a ^ under pointing exactly where the error was detected. attributes err.message short string description of the error type err.line line number of the error in the original source (indexing starts at 1) err.column column number of the error in the original source (indexing starts at 1) install With npm do: npm install syntax-error license MIT Private pa
As promised, we're going to take a closer look at the Error object that gets passed into the catch clause to see just what we can extract from it in an event of an error. The Error object in all browsers support the http://www.javascriptkit.com/javatutors/trycatch2.shtml following two properties: name: The name of the error, or more specifically, the name of the constructor function the error belongs to. message: A description of the error, with this description varying depending on the browser. try{ document.body.filters[0].apply() } catch(e){ alert(e.name + "\n" + e.message) } Demo: Six possible values can be returned by the name property, which as mentioned correspond to the names of the error's constructors. They are: Error Name Description EvalError An error in syntax error the eval() function has occurred. RangeError Out of range number value has occurred. ReferenceError An illegal reference has occurred. SyntaxError A syntax error within code inside the eval() function has occurred. All other syntax errors are not caught by try/catch/finally, and will trigger the default browser error message associated with the error. To catch actual syntax errors, you may use the onerror event. TypeError An error in the expected variable type has occurred. URIError An error when encoding java script error or decoding the URI has occurred (ie: when calling encodeURI()). This level of detail may be useful when you wish to sniff out a specific type of error in your catch clause. In the below, no DIV on the page exists with ID="mydiv". When trying to set its .innerHTML property, a TypeError occurs, since we're trying to assign the .innerHTML property to a null object: try{ document.getElementById("mydiv").innerHTML='Success' //assuming "mydiv" is undefined } catch(e){ if (e.name.toString() == "TypeError"){ //evals to true in this case //do something } } Ok, so maybe it's not that useful most of the time, but you just never know. Throwing your own errors (exceptions) Instead of waiting for one of the 6 types of errors above to occur before control is automatically transferred from the try block to the catch block, you can also explicitly throw your own exceptions to force that to happen on demand. This is great for creating your own definitions of what an error is and when control should be transferred to catch. To throw an error, invoke, well, the throw statement inside your try/catch/finally blocks. The syntax is: throw myerrorobject Where myerrorobject can in fact be anything from a string, number, Boolean, to a new or one of the 6 default Error Constructor functions. What myerrorobject is set to mainly just affects what error.name and error.message returns in your catch clau