如何在 Javascript 中的函数之间传递变量？

Question

Here are 2 functions in the simplest form. I'm working with jquery.

What is the best way to pass var str from the first function to the second one?

function a() {
    var str = "first";
};

function b() {
    var new = str + " second";
};

Answer 1

Use function parameters, like this:

function a() {
   var str = "first";
   b(str);
}

function b(s) {
   var concat = s + " second";
   //do something with concat here...
}

You could just declare a variable higher up in the scope chain, but I opt to use arguments to restrict variable access to only the contexts that absolutely need it.

Oh yeah, isn't that called the principle of least privilege ?

Answer 2

You need to either pass it between them, or it seems from your example, just declare it in a higher scope:

var str;
function a(){
  str="first";
}
function b(){
  var something = str +" second"; //new is reserved, use another variable name
}

Answer 3

i use..

 function a(){
 let str = "first";
 localStorage.setItem('value1', `${str}`);}

 function b(){
 let str = localStorage.getItem('value1');
 let new = str + " second";}