[Javascript] ES2015 - Default args, Spread operator

Default args

可以將在function的參數給予預設值

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function fnWithDefaultArg(a,b=[]){
    // some codes
}

Spread operator

The spread operator allows an expression to be expanded in places where multiple arguments (for function calls) or multiple elements (for array literals) are expected.

function fn(a,b,c){
  // some codes
}
var args = [1,2,3];
fn(...args); <= spread operator

A more powerful array literal

1 2	var parts = ['shoulders', 'knees']; var lyrics = ['head', ...parts, 'and', 'toes']; // ["head", "shoulders", "knees", "and", "toes"]

A better push

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var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];
arr1.push(...arr2);