我如何在 javascript 中使用它

Question

hello i am trying to access the length of an arrary i made inside a function how do i use the "this" to access it. Here is my code

let hashtable = new Arrary(50)
// create a hashfunction 
let gethash = (key)=>{
    // make sure all value passed in are strings 
        let keyStr = key.toString();
        let sum = 0
        for (let i = 0; i < keyStr.length; i++) {
            sum =+ keyStr.charAt(i)
        }
        return sum % this.hashtable.length

}

I am learning hashmaps in data structure and algorithm, i want to use the the length of the hash table to ensure that my hashfunction falls between the size of the arrary

Answer 1

Does it not work without the this keyword?

let hashtable = new Arrary(50)
// create a hashfunction 
let gethash = (key)=>{
    // make sure all value passed in are strings 
        let keyStr = key.toString();
        let sum = 0
        for (let i = 0; i < keyStr.length; i++) {
            sum =+ keyStr.charAt(i)
        }
        return sum % hashtable.length

}

You aren't accessing something bound to a class or object, so you should be able to treat it like a normal variable.

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More about the this keyword:

In most cases, the value of this is determined by how a function is called (runtime binding). It can't be set by assignment during execution, and it may be different each time the function is called. ES5 introduced the bind() method to set the value of a function's this regardless of how it's called, and ES2015 introduced arrow functions which don't provide their own this binding (it retains the this value of the enclosing lexical context).

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