报错

function sum(num1,num2) {
    return num1+num2;
}
rus = sum(num1,num2)
//rus =sum(7,8)
console.log(rus)

报错

[Running] node "/Users/ivyone/44.js"
/Users/ivyone/44.js:4
rus = sum(num1,num2)
          ^

ReferenceError: num1 is not defined
    at Object.<anonymous> (/Users/ivyone/44.js:4:11)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

不报错

function sum(num1,num2) {
    return num1+num2;
}
rus =sum(7,8)
console.log(rus)

不报错

[Running] node "/Users/ivyone/44.js"
15