在函数内部更改全局变量而不调用它

Question

I am right now working on a messenger bot. I am still new to javascript and I been stuck with this proplem in 5 days...

I am trying to change a value if "text" = "javascript" like this:

  function test() {
      if (text === 'javascript') {
          githubSearch = "javascript";
      }
  };

I got a global variable named githubSearch outside the function looking like this:

var githubSearch;

Then I got a variable outside the function named githubRepo where I call githubSearch:

var githubRepo = "https://github.com/search?o=desc&q=" + githubSearch + "&s=stars&type=Repositories&utf8=%E2%9C%93";

My proplem is I need to apply the changes I make in the if statement without calling the function, how can I do this?

Answer 1

When you assign a string to variable 'githubRepo', it stays as it is. Only way to overwrite that is to reassign something to 'githubRepo'.

One way to do what you are trying to do is to use a function that return right URL instead of variable.

var searchType = 'foo';
var getRepoAddress = function(s){
   return 'https://'+s+'/index.html';
};
console.log(getRepoAddress(searchType));
searchType = 'bar';
console.log(getRepoAddress(searchType));

In this example the function takes in as an argument the searchType instead of using variable from outer function scopes. This is considered good practice because functions can now be understood and tested as it is without needing to read lines outside the function.

Also, it looks like you need to split the first function to two functions so you can call just another one:

function getSearchType(text) {
    if (text === 'javascript') {
        return 'javascript'
    } else {
      return 'not_javascript'
    }
}

function test() {
   var gitHubSearch = getSearchType('foobar');
   // do something with gitHubSearch
}

// elsewhere, check the value again
console.log(getSearchType('javascript'));
console.log(
  getRepoAddress(getSearchType('javascript'))
);