使用“使用严格”，但仍会收到警告

Question

HI guys Im trying to get use to using JSLint and I am getting the 'use strict' warning and after adding it to the function I still get the missing 'use strict' statement

    fs.readFile('file', 'utf8', function (err, data) {
    if (err) { "use strict"; throw err; }
    var obj = JSON.parse(data);
  });

i was curious to what i am doing wrong?

Answer 1

I'm not 100% positive on this, but I've only ever used 'use strict'; at the top of a given .js file, not embedded in the code. And I've not gotten the warning after doing so. Perhaps that's where jslint looks for it.

Further, looking at the documentation for it, use strict should be scoped either to the whole script, (top of the file) or to a given function (top of the function, right after the opening brace). So regardless of jslint's capabilities, that should be fixed.

Answer 2

The location of the "use strict" directive is the issue.

Usages:

// Top of script file
"use strict";
/* ... code ... */

Or:

function b() {
  "use strict";
  /* ... code ... */
}

You're using it inside the block of an if branch.