javascript - Why new Promise.all().then() worked? -

let iconsloaded = new promise((resolve, reject) => {   new promise.all(     object.keys(icons).map(iconname => {       const provider = icons[iconname][2] || defaulticonprovider; // ionicons       return provider.getimagesource(         iconname.replace(replacesuffixpattern, ''),         icons[iconname][0],         icons[iconname][1]       )     })   ).then(sources => {     object.keys(icons)       .foreach((iconname, idx) => iconsmap[iconname] = sources[idx])      // call resolve (and done)     resolve(true);   }) }); 

please me understand above code promise.all()

i know promise object has call() method,but know it's static method, should not used above,eg: new promise.all(),but give me no error. why-why-why...

here source code:

the code above has no error

but, code following wrong..give me error 😭

let p2 = new promise(function(resolve, reject){     console.log('p2 body')   resolve('p2 resolve') })  let p1 = new promise(function(resolve, reject){     console.log('p1 body')   resolve('p1 resolve') })  var p = new promise(function(resolve, reject){    new promise.all([p2,p1])    .then(function(){     console.log('all(p2, p1) then')   })     console.log('p body') })