javascript hashset equivalent code example

Example 1: set in javascript

let mySet = new Set()

mySet.add(1)           // Set [ 1 ]
mySet.add(5)           // Set [ 1, 5 ]
mySet.add(5)           // Set [ 1, 5 ]
mySet.add('some text') // Set [ 1, 5, 'some text' ]
let o = {a: 1, b: 2}
mySet.add(o)

mySet.add({a: 1, b: 2})   // o is referencing a different object, so this is okay

mySet.has(1)              // true
mySet.has(3)              // false, since 3 has not been added to the set
mySet.has(5)              // true
mySet.has(Math.sqrt(25))  // true
mySet.has('Some Text'.toLowerCase()) // true
mySet.has(o)       // true

mySet.size         // 5

mySet.delete(5)    // removes 5 from the set
mySet.has(5)       // false, 5 has been removed

mySet.size         // 4, since we just removed one value

console.log(mySet)
// logs Set(4) [ 1, "some text", {…}, {…} ] in Firefox
// logs Set(4) { 1, "some text", {…}, {…} } in Chrome

Example 2: *args python javascript equivalent

//spread operator
a = [1, 2, 3]

function printArgs(args) {
	console.log(...args)
}

printArgs(a)
//=> 1 2 3

Example 3: graal.js javascript array in java

Context context = Context.newBuilder("js").build();
Value result = context.eval("js", "var list=[1,2,'foo',true]; list;");
if (result.hasArrayElements()) {
    for (int i=0;i<result.getArraySize();i++) {
        System.out.println(result.getArrayElement(i));
    }
}